Cited by 66,709Meta-analysis and systematic reviewsStatistical Methods in Clinical TrialsPsychology Research and Bibliometrics

G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences

Open access
Faul, Franz, Erdfelder, Edgar, Lang, Albert-Georg, Buchner, Axel·2007·Behavior Research Methods

Abstract

G*Power (Erdfelder, Faul, & Buchner, 1996) was designed as a general stand-alone power analysis program for statistical tests commonly used in social and behavioral research. G*Power 3 is a major extension of, and improvement over, the previous versions. It runs on widely used computer platforms (i.e., Windows XP, Windows Vista, and Mac OS X 10.4) and covers many different statistical tests of the t, F, and chi2 test families. In addition, it includes power analyses for z tests and some exact tests. G*Power 3 provides improved effect size calculators and graphic options, supports both distribution-based and design-based input modes, and offers all types of power analyses in which users might be interested. Like its predecessors, G*Power 3 is free.

Verified 2026-10-22 · 1 reference not checked yet

Integrity signals

Registry

Crossref · 10.3758/bf03193146

Cites

89 of 90 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

4 of 34 cited sources checked · 2 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    Sample effect sizes are typically biased estimates of their population counterparts.

    “In addition, sample effect sizes are typically biased estimates of their population counterparts (Richardson, 1996).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Richardson, 1996 source
  • Premisecitation

    In order to compensate for adverse effects in tests of within effects or between-within interactions, the noncentrality parameter and the degrees of freedom of the F distribution can be multiplied by a correction factor.

    “In order to compensate for such adverse effects in tests of within effects or between-within interactions, the noncentrality parameter and the degrees of freedom of the F distribution can be multiplied by a correction factor (Geisser & Greenhouse, 1958;Huynh & Feldt, 1970).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Geisser & Greenhouse, 1958 source

      The Introduction (p. 1) says the paper extends an approximate F-distribution adjustment to treatment effects and treatment-by-group interactions. Its analysis (p. 4) multiplies the numerator and denominator degrees of freedom by ε for those tests. The passages address distributions under the null hypothesis, but do not say that the noncentrality parameter is also multiplied by a correction factor. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites Huynh & Feldt, 1970 source
    • The authors state this as an assumption: The univariate approach to repeated measures assumes sphericity: in the population all variances of the repeated measurements are equal and all correlations between pairs of repeated measurements are equal.
  • Interpretationreasoning

    From a computational standpoint, there is little advantage to using approximate rather than exact methods.

    “Thus, from a computational standpoint, there is little advantage to using approximate rather than exact methods (cf.Bradley, Russell, & Reeve, 1998).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Bradley, Russell, & Reeve, 1998 source
  • Findingnone given

    G*Power 3 contains several procedures for performing power analyses in multivariate designs.

    “G*Power 3 contains several procedures for performing power analyses in multivariate designs (see Table 4).”
    Quote in the paperNot a substantial claim
  • Findingnone given

    G*Power 3 offers power analyses for generic t, F, z, chi-square, and binomial tests for which the noncentrality parameter of the distribution under H1 may be entered directly.

    “G*Power 3 also offers power analyses for generic t, F, z, 2 , and binomial tests for which the noncentrality parameter of the distribution under H 1 may be entered directly.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 51
  • May combine two claims. 25
  • The quote only partly states this claim. 2
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation

    The procedures provided by G*Power 3 to test effects in between-subjects designs with more than two groups are identical to those in G*Power 2.

    “The procedures provided by G*Power 3 to test effects in between-subjects designs with more than two groups (i.e., one-way ANOVA designs and general main effects and interactions in factorial ANOVA designs of any order) are identical to those in G*Power 2 (Erdfelder et al., 1996).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Erdfelder et al., 1996 source

      The Program Handling section describes GPOWER procedures for one-way ANOVA and for tests of effects and interactions in multifactorial ANOVA. It does not discuss G*Power 3, so it cannot establish that the two versions’ procedures are identical. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
  • May combine two claims.

    Findingcitation

    G*Power 3 provides one-sample tests for the point-biserial model and for correlations between two normally distributed variables.

    “One-sample tests are provided for the point-biserial model-that is, the model for correlations between a binary variable and a continuous variable-and for correlations between two normally distributed variables”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim.

    Findingnone given

    G*Power 3 supports both distribution-based and design-based input modes.

    “supports both distribution-based and design-based input modes”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    G*Power provides separate but very similar routines for the analysis of between effects, within effects, and interactions in simple A x B designs.

    “G*Power provides separate but very similar routines for the analysis of between effects, within effects, and interactions in simple A B designs”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. May combine two claims.

    Findingnone given

    G*Power 3 provides improved effect size calculators and graphic options.

    “G*Power 3 provides improved effect size calculators and graphic options”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Findingnone given

    New in G*Power 3 are procedures for analyzing main effects and interactions for A x B mixed designs.

    “New in G*Power 3 are procedures for analyzing main effects and interactions for A B mixed designs”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingreasoning

    The Windows and Mac versions of G*Power 3 are essentially equivalent.

    “The Windows and Mac versions of the program are essentially equivalent.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingcitation

    G*Power 3 now includes all tests on proportions considered by Cohen (1988), including the sign test, the z tests for the difference between two proportions, and the chi-square tests for goodness-of-fit and contingency tables.

    “In particular, all tests on proportions considered by Cohen (1988) are now available, including the sign test (chap.5), the z tests for the difference between two proportions (chap.6), and the 2 tests for goodness-of-fit and contingency tables (chap.7).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Cohen (1988)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Findingnone given

    G*Power 3 runs on the personal computer platforms currently in widest use: Windows XP, Windows Vista, and Mac OS X 10.4.

    “G*Power 3 runs on the personal computer platforms currently in widest use: Windows XP, Windows Vista, and Mac OS X 10.4.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingcitation

    The two-sample test for differences between two correlations uses Cohen's effect size q and is based on Fisher's r-to-z transformation.

    “The two-sample test for differences between two correlations uses Cohen's (1988, chap. 4) effect size q and is based on Fisher's r-to-z transformation.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Cohen, 1988

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    G*Power 3 runs on Windows XP, Windows Vista, and Mac OS X 10.4.

    “It runs on widely used computer platforms (i.e., Windows XP, Windows Vista, and Mac OS X 10.4)”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    G*Power 3 is free.

    “Like its predecessors, G*Power 3 is free.”
    Quote in the paperNot a substantial claim
  • The quote only partly states this claim.

    Findingcitation

    G*Power 3 can handle pure repeated measures designs without any between-subjects factors by choosing the Repeated measures: Within factors, ANOVA-approach procedure and setting the number of groups to 1.

    “G*Power 3 can easily handle pure repeated measures designs without any between-subjects factors (see, e.g., Frings & Wentura, 2005;Schwarz & Müller, 2006) by choosing the”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Frings & Wentura, 2005 source
    • cites Schwarz & Müller, 2006 source
  • Classified as probably not a substantial claim.

    Findingnone given

    Statistical tests can be specified in G*Power 3 using two different approaches: distribution-based and design-based.

    “statistical tests can be specified in G*Power 3 using two different approaches: the distribution-based approach and the design-based approach.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingcitation

    Both the univariate and the multivariate approaches to repeated measures are supported.

    “Both the univariate and the multivariate approaches to repeated measures (O'Brien & Kaiser, 1985) are supported.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites O'Brien & Kaiser, 1985 source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given

    The sign test is implemented in G*Power 3 as a special case (c = .5) of the more general binomial test, which is also available in G*Power 3, that a single proportion has a specified value c.

    “The sign test is implemented as a special case (c .5) of the more general binomial test (also available in G*Power 3) that a single proportion has a specified value c.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Findingnone given

    All these multivariate tests belong to the F test family.

    “All these tests belong to the F test family.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. May combine two claims.

    Findingnone given

    G*Power 3 provides procedures to calculate the power for global effects in a one-way MANOVA and for special effects and interactions in factorial MANOVA designs.

    “G*Power 3 provides procedures to calculate the power for global effects in a one-way MANOVA and for special effects and interactions in factorial MANOVA designs.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: In the MANOVA model, the rows of the error matrix are independent p-variate normal random vectors with mean 0 and a positive definite covariance matrix.
  • May combine two claims.

    Findingnone given

    G*Power 3 includes power analyses for z tests and some exact tests.

    “In addition, it includes power analyses for z tests and some exact tests.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given

    The Windows and Mac versions use the same computational routines and share very similar user interfaces.

    “They use the same computational routines and share very similar user interfaces.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    G*Power provides three separate yet very similar routines to calculate power in the univariate approach for between effects, within effects, and interactions.

    “G*Power provides three separate yet very similar routines to calculate power in the univariate approach for between effects, within effects, and interactions.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    G*Power 3 supports enhanced graphics features.

    “G*Power 3 supports users with enhanced graphics features.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingcitation

    The test for correlations between two normally distributed variables uses the exact sample correlation coefficient distribution or, optionally, a large-sample approximation based on Fisher's r-to-z transformation.

    “The latter test uses the exact sample correlation coefficient distribution (Barabesi & Greco, 2002) or, optionally, a large-sample approximation based on Fisher's r-to-z transformation.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Barabesi & Greco, 2002 source
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    In generic routines, the parameters of the central and noncentral distributions are specified directly.

    “In generic routines, the parameters of the central and noncentral distributions are specified directly.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    The G*Power 3 Web page offers an expanding Web-based tutorial describing how to use the program, along with examples.

    “The G*Power 3 Web page offers an expanding Webbased tutorial describing how to use the program, along with examples.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingreasoning

    These offset procedures are available in the Exact test family as Proportions: Inequality (offset), two independent groups (unconditional).

    “These procedures are available in the”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingreasoning

    The main disadvantage of the generic routines is that the dependence of the noncentrality parameter on the sample size is implicit; as a consequence, a priori analyses cannot be performed automatically and N must be iterated by hand.

    “The main disadvantage of the generic routines is, however, that the dependence of the noncentrality parameter on the sample size is implicit.As a consequence, we cannot perform a priori analyses automatically.Rather, we need to iterate N by hand until we find an appropriate power value.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given

    The McNemar exact procedure is very efficient, but for very large sample sizes the exact computation may take too much time.

    “This procedure is very efficient, but for very large sample sizes the exact computation may take too much time.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given

    The preferred input method and the test statistic to use can be changed in the Options dialog.

    “The preferred input method (proportions, difference, risk ratio, or odds ratio; see Table 6) and the test statistic to use (see Table 7) can be changed in the Options dialog.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    In G*Power 3's z test for two independent proportions, one can choose whether Cohen's effect size measure h or two proportions are used to specify the alternate hypothesis.

    “Besides these two computational options, one can also choose whether Cohen's effect size measure h or, alternatively, two proportions are used to specify the alternate hypothesis.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    In the exact unconditional procedure for approximate test statistics, the actual Type I error level can be larger than the nominal level.

    “Note that the actual level can be larger than the nominal level!”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    The simplest procedure in G*Power 3 for testing equality of two independent proportions is a z test with optional arcsin transformation and optional continuity correction.

    “The simplest procedure is a z test with optional arcsin transformation and optional continuity correction.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim.

    Findingnone given

    G*Power 3 provides a group of procedures to test the hypothesis that the difference, risk ratio, or odds ratio of a proportion with respect to a specified reference proportion is different under H1 from a difference, risk ratio, or odds ratio of the same reference proportion assumed in H0.

    “G*Power 3 also provides a group of procedures to test the hypothesis that the difference, risk ratio, or odds ratio of a proportion with respect to a specified reference proportion is different under H 1 from a difference, risk ratio, or odds ratio of the same reference proportion assumed in H 0 .”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing), S4 (based).

    Findingcitation

    With continuity correction on and arcsin transform off, G*Power 3 computes the corrected chi-square approximation (Fleiss, 1981).

    “with”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Fleiss, 1981

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    Copies of the Mac and Windows versions of G*Power 3 are available only at www.psycho.uni-duesseldorf.de/abteilungen/aap/gpower3.

    “Copies of the Mac and Windows versions are available only at www .psycho.uni-duesseldorf.de/abteilungen/aap/gpower3.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). The quote only partly states this claim.

    Findingcitation

    With both continuity correction and arcsin transform off, G*Power 3 computes the uncorrected chi-square approximation (Fleiss, 1981).

    “With both”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Fleiss, 1981

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given

    Plots of the central and noncentral distributions are shown only for tests based on the t, F, z, chi-square, or binomial distribution; no plots are shown for tests that involve an enumeration procedure, such as the McNemar test.

    “Plots of the central and noncentral distributions are shown only for tests based on the t, F, z, 2 , or binomial distribution.No plots are shown for tests that involve an enumeration procedure (e.g., the McNemar test).”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given

    G*Power 3 is a noncommercial program that can be downloaded free of charge.

    “Like its predecessor, G*Power 3 is a noncommercial program that can be downloaded free of charge.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingreasoning

    A limiting N can be specified in the Options dialog that determines at which sample size G*Power 3 switches to a large sample approximation.

    “Therefore, a limiting N can be specified in the Options dialog that determines at which sample size G*Power 3 switches to a large sample approximation.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Findingnone given

    In tests without offset, the different input parameters (e.g., differences, risk ratio) are equivalent ways of specifying two proportions, and the specific choice has no influence on the results.

    “In the tests without offset, the different input parameters (e.g., differences, risk ratio) are equivalent ways of specifying two proportions.The specific choice has no influence on the results.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingreasoning

    G*Power 3 offers separate power analyses for point-biserial correlations (in the t family of distributions) and correlations between two normally distributed variables (in the exact distribution family).

    “For this reason, G*Power 3 offers separate power analyses for point-biserial correlations (in the t family of distributions) and correlations between two normally distributed variables (in the exact distribution family).”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    Users who provide their e-mail addresses will be informed of updates.

    “Users who let us know their e-mail addresses will be informed of updates.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    Normally, G*Power 3 calculates the exact unconditional power.

    “Normally, G*Power 3 calculates the exact unconditional power.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Findingnone given

    G*Power 3 always requires the actual alpha not to be larger than the nominal alpha value.

    “G*Power 3 always requires the actual not to be larger than the nominal value.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    Despite the highly optimized algorithm used in G*Power 3, long computation times may result for large sample sizes (e.g., N > 1,000).

    “However, despite the highly optimized algorithm used in G*Power 3, long computation times may result for large sample sizes (e.g., N 1,000).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingcitation

    For both the sign test and the binomial test, G*Power 3 uses Cohen's (1988) effect size g and calculates exact power values based on the binomial distribution.

    “In both procedures, Cohen's (1988) effect size g is used and exact power values based on the binomial distribution are calculated.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Cohen's (1988)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    In tests with offset, each input method has a different set of available test statistics.

    “In the case of tests with offset, however, each input method has a different set of available test statistics.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    G*Power 3 offers all types of power analyses in which users might be interested.

    “offers all types of power analyses in which users might be interested.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisecitation

    Both the Muller and Peterson and O'Brien and Shieh approaches approximate the exact distributions of Wilks's U, Hotelling-Lawley T1, Hotelling-Lawley T2, and Pillai's V by F distributions and are asymptotically equivalent.

    “Both approaches approximate the exact distributions of Wilks's U (Rao, 1951), the Hotelling-Lawley T 1 (Pillai & Samson, 1959), the Hotelling-Lawley T 2 (McKeon, 1974), and Pillai's V (Pillai & Mijares, 1959) by F distributions and are asymptotically equivalent.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Rao, 1951
    • cites Pillai & Samson, 1959 source
    • cites McKeon, 1974 source
    • The authors state this as an assumption: In the MANOVA model, the rows of the error matrix are independent p-variate normal random vectors with mean 0 and a positive definite covariance matrix.
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    T2 seems not very well suited for a priori analyses.

    “Thus, this test statistic seems not very well suited for a priori analyses.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Cohen defines qs of 0.10, 0.30, and 0.50 as small, medium, and large effects, respectively.

    “Cohen defines qs of 0.10, 0.30, and 0.50 as small, medium, and large effects, respectively.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Cohen, 1988

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Cohen defines ds of 0.2, 0.5, and 0.8 as small, medium, and large effects, respectively.

    “Cohen defines ds of 0.2, 0.5, and 0.8 as small, medium, and large effects, respectively.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Cohen, 1988

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationcitation

    The assumption that the sample effect size is essentially identical to the population effect size is likely to be false, and more so the smaller the sample.

    “Obviously, this assumption is likely to be false, and the more so the smaller the sample.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given

    G*Power 3 is a major extension of and improvement over previous versions.

    “G*Power 3 is a major extension of, and improvement over, the previous versions.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The Hotelling T2 tests are extensions of univariate t tests to the multivariate case.

    “The Hotelling T 2 tests are extensions of univariate t tests to the multivariate case, in which more than one dependent variable is measured”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rencher, 1998
  • May combine two claims.

    Interpretationcitation

    The approximations of O'Brien and Shieh for s>1 eigenvalues are almost always more accurate than those of Muller and Peterson's method, which systematically underestimates power.

    “its approximations for s 1 eigenvalues are almost always more accurate than those of Muller and Peterson's method (which systematically underestimates power)”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites O'Brien & Shieh, 1999

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • The authors state this as an assumption: In the MANOVA model, the rows of the error matrix are independent p-variate normal random vectors with mean 0 and a positive definite covariance matrix.
  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationnone given

    G*Power 3 is a major extension of, and improvement over, G*Power 2 in that it offers easy-to-apply power analyses for a much larger variety of common statistical tests.

    “To summarize, G*Power 3 is a major extension of, and improvement over, G*Power 2 in that it offers easy-toapply power analyses for a much larger variety of common statistical tests.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    If the degrees of freedom reported by G*Power do not match those reported by the program used to analyze the sample data, the input provided to G*Power is incorrect and the power calculations do not apply.

    “If the degrees of freedom do not match, the input provided to G*Power is incorrect and the power calculations do not apply.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    The observed power is reported in many frequently used computer programs, such as the MANOVA procedure of SPSS.

    “The observed power is reported in many frequently used computer programs (e.g., the MANOVA procedure of SPSS).”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given

    Program handling in G*Power 3 is more flexible, easier to understand, and more intuitive than in G*Power 2, reducing the risk of erroneous applications.

    “Program handling is more flexible, easier to understand, and more intuitive than in G*Power 2, reducing the risk of erroneous applications.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The subroutines used to compute the distribution functions (and the inverse) of the noncentral t, F, chi-square, z, and binomial distributions are based on the C version of DCDFLIB, slightly modified for G*Power 3.

    “The subroutines used to compute the distribution functions (and the inverse) of the noncentral t, F, 2 , z, and binomial distributions are based on the C version of the DCDFLIB (available from www.netlib.org/random/),which was slightly modified for our purposes.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

    Premisenone given

    Four-digit precision of power calculations may be mandatory in many applications.

    “First, four-digit precision of power calculations may be mandatory in many applications.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisereasoning

    Due to the discrete nature of the binomial distribution, the nominal alpha value usually cannot be realized.

    “Note, however, that, due to the discrete nature of the binomial distribution, the nominal value of usually cannot be realized.”
    Quote in the paperNot a substantial claim
63 of 63
  • The authors state this as an assumption.

    The univariate approach to repeated measures assumes sphericity: in the population all variances of the repeated measurements are equal and all correlations between pairs of repeated measurements are equal.

    “The univariate approach is based on the sphericity assumption.This assumption is correct if (in the population) all variances of the repeated measurements are equal and all correlations between pairs of repeated measurements are equal.”
  • The authors state this as an assumption.

    In the MANOVA model, the rows of the error matrix are independent p-variate normal random vectors with mean 0 and a positive definite covariance matrix.

    “The rows of are taken to be independent p-variate normal random vectors with mean 0 and p p positive definite covariance matrix .”
  • The authors state this as an assumption.

    In G*Power 3, the constant vector in the multivariate general linear hypothesis H0: CBA=0 is assumed to be zero.

    “in G*Power 3, 0 is assumed to be zero”
3 of 3

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • An a priori sample-size estimate indicated at least 30 participants per group were needed to allow for a 20% dropout rate.

    “The estimate was that we needed at least 30 participants per group to account for a 20% dropout rate.”

    From Postoperative Physiotherapy in Women Undergoing Pelvic Floor Reconstructive Surgery: A Randomized Controlled Clinical Trial (2022) · cites this paper as [16]

    The A Priori Power Analyses section (page unavailable) explains how to calculate a sample size before a study. It does not report the citing study’s estimate of 30 participants per group or a 20% dropout allowance; its example of groups of 30 in Tests for Means concerns a different calculation. (LLM, conf=0.82)

    Experimental — accuracy not yet measured
  • A statistical power analysis was performed using GPower 3.1 to estimate sample size for a comparison of differences between two dependent means (matched pairs).

    “A statistical power analysis was performed using GPower 3.1 [72,73] to estimate sample size for a comparison of differences between two dependent means (matched pairs).”

    From Walking Green: Developing an Evidence Base for Nature Prescriptions (2019) · cites this paper as [72]

    The 'Tests for Means (Univariate Case)' section says G*Power 3 supports tests of two dependent means (matched pairs), and 'A Priori Power Analyses' says it can compute the required sample size. This 2007 paper describes G*Power 3, however, not the specifically named version 3.1. (LLM, conf=0.87)

    Experimental — accuracy not yet measured
  • A minimum sample size of n = 1145 was needed to detect a small effect size (f2 = 0.02) for the eight-predictor Comprehensive School Survey difference-in-difference regression models, based on alpha = 0.05 and power = 0.95.

    “According to G*Power v3.1.97(Faul et al., 2007), a minimum sample size of n = 1145 was needed to detect a small effect size (f 2 = 0.02) for our eight-predictor Comprehensive School Survey (CSS) difference-in-difference (DiD) regression models, based on α = 0.05 and, conservatively, power = 0.95.”

    From Restorative Practices: Using local evidence on costs and student outcomes to inform school district decisions about behavioral interventions (2022) · cites this paper as Faul et al., 2007

    The paper’s ‘A Priori Power Analyses’ section says G*Power computes sample size from power, significance level, and effect size; ‘Tests for Correlation and Regression’ describes multiple-regression procedures and identifies f² = 0.02 as a small effect. Our copy does not report n = 1145 for the citing authors’ eight-predictor CSS difference-in-difference models or identify version 3.1.97, so it does not verify that specific calculation. (LLM, conf=0.86)

    Experimental — accuracy not yet measured
  • A minimum sample size of eight individuals was determined at power 0.80 (two-tailed α = 0.05) and effect size for enjoyment equal to 1.0.

    “At a power equal to 0.80 (two-tailed α = 0.05) and effect size for enjoyment equal to 1.0, a minimum sample size of eight individuals was determined [26] which is similar to a previous study [12].”

    From High-Intensity Interval Training Elicits Higher Enjoyment than Moderate Intensity Continuous Exercise (2017) · cites this paper as [26]

    The A Priori Power Analyses section (page unavailable) explains that G*Power calculates sample size from a specified power, significance level, and effect size. It does not report an enjoyment effect size of 1.0 or establish that eight individuals is the minimum for the citing study’s design. (LLM, conf=0.84)

    Experimental — accuracy not yet measured
  • According to G*Power's calculation, a conservative Wilcoxon-Mann-Whitney two-tailed test requires 90 participants per condition to detect medium-sized effects (Cohen's d = 0.5) at alpha = 0.05 with power (1-beta) = 0.90.

    “According to G*Power's calculation, a conservative WilcoxonMann-Whitney two-tailed test requires 90 participants per condition to detect medium-sized effects (Cohen's d = 0.5) at the significance level of 𝛼 = 0.05 with power (1𝛽 ) = 0.90.”

    From "I'm Not Sure, But...": Examining the Impact of Large Language Models' Uncertainty Expression on User Reliance and Trust (2024) · cites this paper as [39]

    The Program Handling section describes G*Power as a program for a priori sample-size calculations, and the Tests for Means section identifies d = 0.5 as a medium effect. Our copy does not report a Wilcoxon–Mann–Whitney calculation requiring 90 participants per condition at the stated alpha and power; the paper’s numerical example instead concerns a one-tailed t test with different inputs. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

Cites

Flagged first, then by citations

Research works printed but not linked: 5

  1. Bredenkamp, J. (1969). Über die Anwendung von Signifikanztests bei Theorie-testenden Experimenten [The application of significance tests in theory-testing experiments].Psychologische Beiträge,11, 275–285.
  2. Field, A. P. (2005).Discovering statistics with SPSS (2nd ed.). London: Sage.
  3. Ortseifen, C., Bruckner, T., Burke, M., &Kieser, M. (1997). An overview of software tools for sample size determination.Informatik, Biometrie & Epidemiologie in Medizin & Biologie,28, 91–118.
  4. Pillai, K. C. S., &Samson, P., Jr. (1959). On Hotelling’s generalization ofT 2.Biometrika,46, 160–168.
  5. Rasch, B., Friese, M., Hofmann, W. J., &Naumann, E. (2006b).Quantitative Methoden 2: Einführung in die Statistik (2. Auflage) [Quantitative methods 2: Introduction to statistics (2nd ed.)]. Heidelberg, Germany: Springer.

Cited by

Sorted by citations

Authors
Faul, F., Erdfelder, E., Lang, A.-G., & Buchner, A.
Affiliations
  • Christian-Albrechts-Universität zu Kiel (DE)
  • University of Mannheim (DE)
  • Heinrich Heine University Düsseldorf (DE)
Corresponding author
  • Faul, Franz
  • Erdfelder, Edgar
Venue
Behavior Research Methods
Published
2007-05
Volume
39
Issue
2
Pages
175-191
ISSN
  • 1554-351X (ISSN-L)
  • 1554-3528
OpenAlex
W2087484885
Cited by
65,971
References
87
Citations by year
2026: 7176 · 2025: 8198 · 2024: 7515 · 2023: 6707 · 2022: 6648 · 2021: 6060 · 2020: 4945 · 2019: 3657 · 2018: 3053 · 2017: 2495 · 2016: 2029 · 2015: 1719 · 2014: 1371 · 2013: 1155 · 2012: 938
FWCI
527.50
Type
journal article
Language
en
Open access
Locations
  • Behavior Research Methods (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Psychology Research and Bibliometrics
Keywords
statistical power analysis, effect size estimation, t-test, F-test, chi-square test, Z-test, exact tests
MeSH terms
Algorithms, Behavioral Sciences, Data Interpretation, Statistical, Mathematical Computing, Microcomputers, Sensitivity and Specificity, Social Sciences, Software, Statistics, Nonparametric, Biomedical Research

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-22.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-22.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review