Genetic and environmental determinants of stressful life events and their overlap with depression and neuroticism
Open accessPublished version of a preprint
Abstract
Background: Stressful life events (SLEs) and neuroticism are risk factors for major depressive disorder (MDD). However, SLEs and neuroticism are heritable and genetic risk for SLEs is correlated with risk for MDD. We sought to investigate the genetic and environmental contributions to SLEs in a family-based sample, and quantify genetic overlap with MDD and neuroticism. Methods: A subset of Generation Scotland: the Scottish Family Health Study (GS), consisting of 9618 individuals with information on MDD, past 6 month SLEs, neuroticism and genome-wide genotype data was used in the present study. We estimated the heritability of SLEs using GCTA software. The environmental contribution to SLEs was assessed by modelling familial, couple and sibling components. Using polygenic risk scores (PRS) and LD score regression (LDSC) we analysed the genetic overlap between MDD, neuroticism and SLEs. Results: Past 6-month life events were positively correlated with lifetime MDD status (β=0.21, r 2 =1.1%, p=2.5 x 10 -25 ) and neuroticism (β =0.13, r 2 =1.9%, p=1.04 x 10 -37 ) at the phenotypic level. Common SNPs explained 8% of the phenotypic variance in personal life events (those directly affecting the individual) (S.E.=0.03, p= 9 x 10 -4 ). A significant effect of couple environment was detected accounting for 13% (S.E.=0.03, p=0.016) of the phenotypic variation in SLEs. PRS analyses found that reporting more SLEs was associated with a higher polygenic risk for MDD (β =0.05, r 2 =0.3%, p=3 x 10 -5 ), but not a higher polygenic risk for neuroticism. LDSC showed a significant genetic correlation between SLEs and both MDD (r G =0.33, S.E.=0.08 ) and neuroticism (r G =0.15, S.E.=0.07). Conclusions: These findings suggest that SLEs should not be regarded solely as environmental risk factors for MDD as they are partially heritable and this heritability is shared with risk for MDD and neuroticism. Further work is needed to determine the causal direction and source of these associations.
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
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?
Experiencing maltreatment in childhood increases the likelihood of exhibiting an unfavourable course of illness, with higher rates of recurrence and persistence in adulthood.
“Moreover, convincing evidence indicates that experiencing maltreatment in childhood increases the likelihood of exhibiting an unfavourable course of illness, with higher rates of recurrence and persistence in adulthood. 267”
From Time for united action on depression: a Lancet–World Psychiatric Association Commission (2022) · cites this paper as [267]
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
The self-check needs the paper’s full text.
Cites
PLINK: a tool set for whole-genome association and population-based linkage analyses.
Purcell, S., Neale, B., Todd-Brown, K., Thomas, L., Ferreira, M. A. R., Bender, D., Maller, J., Sklar, P., de Bakker, P. I. W., Daly, M. J., et al. (2007) · The American Journal of Human Genetics · doi:10.1086/519795 · Cited by 34,089 · see citing works
GCTA: a tool for genome-wide complex trait analysis
Yang, J., Lee, S. H., Goddard, M. E., & Visscher, P. M. (2011) · The American Journal of Human Genetics · doi:10.1016/j.ajhg.2010.11.011 · Cited by 8,279 · see citing works
Kessler, R. C., Berglund, P., Demler, O., Jin, R., Koretz, D., Merikangas, K. R., Rush, A. J., Walters, E. E., & Wang, P. S. (2003) · JAMA · doi:10.1001/jama.289.23.3095 · Cited by 7,988 · see citing works
LD Score regression distinguishes confounding from polygenicity in genome-wide association studies
Schizophrenia Working Group of the Psychiatric Genomics Consortium, Bulik-Sullivan, B. K., Loh, P.-R., Finucane, H. K., Ripke, S., Yang, J., Patterson, N., Daly, M. J., Price, A. L., & Neale, B. M. (2015) · Nature Genetics · doi:10.1038/ng.3211 · Cited by 5,559 · see citing works
Causal Relationship Between Stressful Life Events and the Onset of Major Depression
Kendler, K. S., Karkowski, L. M., & Prescott, C. A. (1999) · American Journal of Psychiatry · doi:10.1176/ajp.156.6.837 · Cited by 2,486 · see citing works
THE EFFECTS OF STRESSFUL LIFE EVENTS ON DEPRESSION
Kessler, R. C. (1997) · Annual Review of Psychology · doi:10.1146/annurev.psych.48.1.191 · Cited by 2,111 · see citing works
Generation of stress in the course of unipolar depression.
Hammen, C. (1991) · Journal of Abnormal Psychology · doi:10.1037//0021-843x.100.4.555 · Cited by 1,446 · see citing works
PRSice: Polygenic Risk Score software
Euesden, J., Lewis, C. M., & O’Reilly, P. F. (2014) · Bioinformatics · doi:10.1093/bioinformatics/btu848 · Cited by 1,149 · see citing works
Brugha, T. S., Bebbington, P., Tennant, C., & Hurry, J. (1985) · Psychological Medicine · doi:10.1017/s003329170002105x · Cited by 1,108 · see citing works
Generation of stress in the course of unipolar depression.
Hammen, C. L. (1991) · Journal of Abnormal Psychology · doi:10.1037/0021-843x.100.4.555 · Cited by 1,078 · see citing works
Stressful life events, genetic liability, and onset of an episode of major depression in women
(1995) · American Journal of Psychiatry · doi:10.1176/ajp.152.6.833 · Cited by 1,063 · see citing works
Study, L. C., Okbay, A., Baselmans, B. M. L., De Neve, J.-E., Turley, P., Nivard, M. G., Fontana, M. A., Meddens, S. F. W., Linnér, R. K., Rietveld, C. A., et al. (2016) · Nature Genetics · doi:10.1038/ng.3552 · Cited by 1,013 · see citing works
Advantages and pitfalls in the application of mixed-model association methods
Yang, J., Zaitlen, N. A., Goddard, M. E., Visscher, P. M., & Price, A. L. (2014) · Nature Genetics · doi:10.1038/ng.2876 · Cited by 981 · see citing works
Cortés, A., Hadler, J. S., Robinson, P. C., Leo, P., Cremin, K., Pryce, K., Harris, J., Bradbury, L. A., Kenna, T., Yang, J., et al. (2013) · Nature Genetics · doi:10.1038/ng.2667 · Cited by 855 · see citing works
Kendler, K. S., Kuhn, J., & Prescott, C. A. (2004) · American Journal of Psychiatry · doi:10.1176/appi.ajp.161.4.631 · Cited by 799 · see citing works
Kessler, R. C., Zhao, S., Blazer, D. G., & Swartz, M. (1997) · Journal of Affective Disorders · doi:10.1016/s0165-0327(97)00056-6 · Cited by 790 · see citing works
Extraversion and neuroticism as predictors of objective life events: A longitudinal analysis.
Magnus, K., Diener, E., Fujita, F., & Pavot, W. (1993) · Journal of Personality and Social Psychology · doi:10.1037/0022-3514.65.5.1046 · Cited by 504 · see citing works
Efficient haplotype matching and storage using the positional Burrows–Wheeler transform (PBWT)
Durbin, R. M. (2014) · Bioinformatics · doi:10.1093/bioinformatics/btu014 · Cited by 427 · see citing works
Smith, B. H., Campbell, A., Linksted, P., Fitzpatrick, B., Jackson, C., Kerr, S. M., Deary, I. J., MacIntyre, D. J., Campbell, H., McGilchrist, M., et al. (2013) · International Journal of Epidemiology · doi:10.1093/ije/dys084 · Cited by 401 · see citing works
Self-citationJylhä, P., & Isometsä, E. (2006) · Depression and Anxiety · doi:10.1002/da.20167 · Cited by 355 · see citing works
Genetic covariation between neuroticism and the symptoms of anxiety and depression
Jardine, R., Martin, N. G., Henderson, A. S., & Rao, D. C. (1984) · Genetic Epidemiology · doi:10.1002/gepi.1370010202 · Cited by 351 · see citing works
KENDLER, K. S., & KARKOWSKI-SHUMAN, L. (1997) · Psychological Medicine · doi:10.1017/s0033291797004716 · Cited by 328 · see citing works
A twin study of recent life events and difficulties.
Kendler, K., Neale, M., Kessler, R. C., Heath, A., & Eaves, L. (1993) · Archives of General Psychiatry · doi:10.1001/archpsyc.1993.01820220041005 · Cited by 288 · see citing works
A direct test of the diathesis-stress model for depression
Major Depressive Disorder Working Group of the Psychiatric Genomics Consortium, Colodro-Conde, L., Couvy-Duchesne, B., Zhu, G., Coventry, W. L., Byrne, E. M., Gordon, S., Wright, M. J., Montgomery, G. W., Madden, P. A. F., et al. (2018) · Molecular Psychiatry · doi:10.1038/mp.2017.130 · Cited by 285 · see citing works
Westman, M., & Vinokur, A. D. (1998) · Human Relations · doi:10.1177/001872679805100202 · Cited by 280 · see citing works
Smith, B. H., Campbell, H., Blackwood, D., Connell, J., Connor, M., Deary, I. J., Dominiczak, A. F., Fitzpatrick, B., Ford, I., Jackson, C. M., et al. (2006) · BMC Medical Genetics · doi:10.1186/1471-2350-7-74 · Cited by 262 · see citing works
Self-citationGenetic influence on life events during the last half of the life span.
Plomin, R. J., Lichtenstein, P., Pedersen, N. L., McClearn, G. E., & al, E. (1990) · Psychology and Aging · doi:10.1037/0882-7974.5.1.25 · Cited by 229 · see citing works
High Dimensional Endophenotype Ranking in the Search for Major Depression Risk Genes
Glahn, D. C., Curran, J. E., Winkler, A. M., Carless, M. A., Kent, J. W., Charlesworth, J., Johnson, M. P., Göring, H. H. H., Cole, S. A., Dyer, T. D., et al. (2011) · Biological Psychiatry · doi:10.1016/j.biopsych.2011.08.022 · Cited by 184 · see citing works
Genomic analysis of family data reveals additional genetic effects on intelligence and personality
Hill, W. D., Arslan, R. C., Xia, C., Luciano, M., Amador, C., Navarro, P., Hayward, C., Nagy, R., Porteous, D. J., McIntosh, A. M., et al. (2018) · Molecular Psychiatry · doi:10.1038/s41380-017-0005-1 · Cited by 158 · see citing works
Self-citationDependent Stressful Life Events and Prior Depressive Episodes in the Prediction of Major Depression
Kendler, K. S., & Gardner, C. O. (2010) · Archives of General Psychiatry · doi:10.1001/archgenpsychiatry.2010.136 · Cited by 156 · see citing works
Dunn, E. C., Wiste, A. K., Radmanesh, F., Almli, L. M., Gogarten, S. M., Sofer, T., Faul, J. D., Kardia, S. L. R., Smith, J. A., Weir, D. R., et al. (2016) · Depression and Anxiety · doi:10.1002/da.22484 · Cited by 114 · see citing works
Life events, anxious depression and personality: a prospective and genetic study
Middeldorp, C. M., Cath, D. C., Beem, A. L., Willemsen, G. A. H. M., & Boomsma, D. I. (2008) · Psychological Medicine · doi:10.1017/s0033291708002985 · Cited by 114 · see citing works
Life events and the onset of affective disorder A longitudinal general population study
SURTEES, P., MILLER, P., INGHAM, J., KREITMAN, N., RENNIE, D., & SASHIDHARAN, S. (1986) · Journal of Affective Disorders · doi:10.1016/0165-0327(86)90047-9 · Cited by 108 · see citing works
The generation of life events in recurrent and non-recurrent depression
Harkness, K. L., Monroe, S. M., Simons, A. D., & Thase, M. E. (1999) · Psychological Medicine · doi:10.1017/s0033291798007752 · Cited by 108 · see citing works
Nagy, R., Boutin, T., Marten, J., Huffman, J. E., Kerr, S. M., Campbell, A., Evenden, L., Gibson, J., Amador, C., Howard, D. M., et al. (2017) · Genome Medicine · doi:10.1186/s13073-017-0414-4 · Cited by 108 · see citing works
Self-citationLife events and personality in late adolescence: Genetic and environmental relations
Billig, J. P., Hershberger, S. L., Iacono, W. G., & McGue, M. K. (1996) · Behavior Genetics · doi:10.1007/bf02361227 · Cited by 79 · see citing works
The Heritability of Life Events: An Adolescent Twin and Adoption Study
Bemmels, H. R., Burt, S., Legrand, L. N., Iacono, W., & McGue, M. (2008) · Twin Research and Human Genetics · doi:10.1375/twin.11.3.257 · Cited by 78 · see citing works
Vinkhuyzen, A. A. E., van der Sluis, S., MAES, H. H. M., & Posthuma, D. (2011) · Behavior Genetics · doi:10.1007/s10519-011-9507-9 · Cited by 71 · see citing works
Navrady, L. B., Wolters, M. K., MacIntyre, D. J., Clarke, T., Campbell, A. I., Murray, A. D., Evans, K. L., Seckl, J. R., Haley, C., Milburn, K., et al. (2017) · International Journal of Epidemiology · doi:10.1093/ije/dyx115 · Cited by 70 · see citing works
Self-citationXia, C., Amador, C., Huffman, J. E., Trochet, H., Campbell, A., Porteous, D. J., Scotland, G., Hastie, N. D., Hayward, C., Vitart, V., et al. (2016) · PLoS Genetics · doi:10.1371/journal.pgen.1005804 · Cited by 68 · see citing works
Self-citationClinical risk factors for the generation of life events in major depression.
Harkness, K. L., & Luther, J. F. (2001) · Journal of Abnormal Psychology · doi:10.1037//0021-843x.110.4.564 · Cited by 55 · see citing works
Recent genomic heritage in Scotland
Amador, C., Huffman, J. E., Trochet, H., Campbell, A. I., Porteous, D. J., Scotland, G., Wilson, J. F., Hastie, N. D., Vitart, V., Hayward, C., et al. (2015) · BMC Genomics · doi:10.1186/s12864-015-1605-2 · Cited by 52 · see citing works
Self-citationStressful Life Events and Depression among Adolescent Twin Pairs
Boardman, J. D., Alexander, K. B., & Stallings, M. C. (2011) · Biodemography and Social Biology · doi:10.1080/19485565.2011.574565 · Cited by 50 · see citing works
Foley, D. L., Neale, M. C., & Kendler, K. S. (1996) · Psychological Medicine · doi:10.1017/s0033291700035960 · Cited by 46 · see citing works
Stress Generation in Depressed Patients and Community Controls
Chun, C., Cronkite, R. C., & Moos, R. H. (2004) · Journal of Social and Clinical Psychology · doi:10.1521/jscp.23.3.390.35453 · Cited by 45 · see citing works
Estimating the heritability of reporting stressful life events captured by common genetic variants
Power, R. A., Wingenbach, T. S. H., Cohen‐Woods, S., Uher, R., Ng, M. Y., Butler, A. W., Ising, M., Craddock, N. J., Owen, M. J., Korszun, A., et al. (2012) · Psychological Medicine · doi:10.1017/s0033291712002589 · Cited by 45 · see citing works
Clinical risk factors for the generation of life events in major depression.
Harkness, K. L., & Luther, J. F. (2001) · Journal of Abnormal Psychology · doi:10.1037/0021-843x.110.4.564 · Cited by 39 · see citing works
Zeng, Y., Navarro, P., Xia, C., Amador, C., Fernandez-Pujals, A. M., Thomson, P. A., Campbell, A. I., Nagy, R., Clarke, T., Hafferty, J. D., et al. (2016) · EBioMedicine · doi:10.1016/j.ebiom.2016.11.003 · Cited by 37 · see citing works
Self-citationGenomic analysis of family data reveals additional genetic effects on intelligence and personalityPreprint
Hill, W. D., Arslan, R. C., Xia, C., Michelle Luciano, A., Amador, C., Navarro, P., Hayward, C., Nagy, R., Porteous, D. J., McIntosh, A. M., et al. (2017) · bioRxiv (Cold Spring Harbor Laboratory) · doi:10.1101/106203 · Cited by 30 · see citing works
Self-citation
Flagged first, then by citations
1 of the 50 references couldn’t be matched to a known paper.
Cited by
Sorted by citations
Time for united action on depression: a Lancet–World Psychiatric Association Commission
Herrman, H., Patel, V., Kieling, C., Berk, M., Buchweitz, C., Cuijpers, P., Furukawa, T. A., Kessler, R. C., Kohrt, B. A., Maj, M., et al. (2022) · The Lancet · doi:10.1016/s0140-6736(21)02141-3 · Cited by 1,104 · see citing works
Childhood maltreatment and DNA methylation: A systematic review
Cecil, C. A. M., Zhang, Y., & Nolte, T. (2020) · Neuroscience & Biobehavioral Reviews · doi:10.1016/j.neubiorev.2020.02.019 · Cited by 171 · see citing works
Arnau‐Soler, A., Macdonald-Dunlop, E., Adams, M. J., Clarke, T., MacIntyre, D. J., Milburn, K., Navrady, L. B., Scotland, G., Hayward, C., McIntosh, A. M., et al. (2019) · Translational Psychiatry · doi:10.1038/s41398-018-0360-y · Cited by 131 · see citing works
Self-citationHur, J., Stockbridge, M. D., Fox, A. S., & Shackman, A. J. (2019) · Progress in brain research · doi:10.1016/bs.pbr.2019.03.012 · Cited by 91 · see citing works
A validation of the diathesis-stress model for depression in Generation Scotland
Arnau‐Soler, A., Adams, M. J., Clarke, T., MacIntyre, D. J., Milburn, K., Navrady, L. B., Generation Scotland, Hayward, C., McIntosh, A. M., & Thomson, P. A. (2019) · Translational Psychiatry · doi:10.1038/s41398-018-0356-7 · Cited by 82 · see citing works
Self-citationThe P-factor and its genomic and neural equivalents: an integrated perspective
Sprooten, E., Franke, B., & Greven, C. U. (2021) · Molecular Psychiatry · doi:10.1038/s41380-021-01031-2 · Cited by 63 · see citing works
Prenatal and childhood adverse life events, inflammation and depressive symptoms across adolescence
Flouri, E., Francesconi, M., Midouhas, E., & Lewis, G. (2019) · Journal of Affective Disorders · doi:10.1016/j.jad.2019.09.024 · Cited by 53 · see citing works
Current Knowledge of the Antidepressant Activity of Chemical Compounds from Crocus sativus L.
Matraszek, R., Chwil, M., Terlecki, K., & Skoczylas, M. M. (2022) · Pharmaceuticals · doi:10.3390/ph16010058 · Cited by 35 · see citing works
Reciprocal effects of neuroticism and life stress in adolescence
Metts, A. V., Yarrington, J. S., Enders, C. K., Hammen, C. L., Mineka, S., Zinbarg, R. E., & Craske, M. G. (2020) · Journal of Affective Disorders · doi:10.1016/j.jad.2020.12.016 · Cited by 29 · see citing works
Crouse, J. J., Park, S. H., Byrne, E. M., Mitchell, B. L., Scott, J. L., Medland, S. E., Lin, T., Wray, N. R., Martin, N. G., & Hickie, I. B. (2024) · Molecular Psychiatry · doi:10.1038/s41380-024-02492-x · Cited by 25 · see citing works
Su, D., Jiang, W., Yuan, Q., Guo, L., Liu, Q., Zhang, M., Kang, C., Xiao, C., Yang, C., Li, L., et al. (2023) · Ecotoxicology and Environmental Safety · doi:10.1016/j.ecoenv.2023.114991 · Cited by 23 · see citing works
Nunes, K. G., & da Rocha, N. S. (2021) · Quality of Life Research · doi:10.1007/s11136-021-02920-3 · Cited by 17 · see citing works
Genetic influences on treatment-seeking for common mental health problems in the UK biobank
Rayner, C., Coleman, J. R. I., Purves, K. L., Cheesman, R., Hübel, C., Gaspar, H. A., Glanville, K. P., Krebs, G., Morneau‐Vaillancourt, G., Breen, G. D., et al. (2019) · Behaviour Research and Therapy · doi:10.1016/j.brat.2019.103413 · Cited by 14 · see citing works
Genetic influences on depression and selection into adverse life experiences
Rauf, T., & Jeremy Freese, A. (2024) · Social Science & Medicine · doi:10.1016/j.socscimed.2024.116633 · Cited by 7 · see citing works
Depresión Infanto-Juvenil y exposición temprana a la violencia
Henao, E. A. O., Díaz, B. A. M., & Valencia, J. B. Z. (2021) · Revista Iberoamericana de Psicología · doi:10.33881/2027-1786.rip.13310 · Cited by 2 · see citing works
Evers, K. C., Borsboom, D., Fried, E. I., Hasselman, F., Bartos̆, F., & Waldorp, L. (2026) · Communications Psychology · doi:10.1038/s44271-026-00394-y
- Authors
- Clarke, T.-K., Zeng, Y., Navrady, L., Xia, C., Haley, C., Campbell, A., Navarro, P., Amador, C., Adams, M. J., Howard, D. M., Soler, A., Hayward, C., Thomson, P. A., Smith, B. H., Padmanabhan, S., Hocking, L. J., Hall, L. S., Porteous, D. J., Major Depressive Disorder Working Group of the Psychiatric Genomics Consortium, Deary, I. J., & McIntosh, A. M.
- Affiliations
- Flinders University (AU)
- Institute of Genetics and Cancer (GB)
- Cardiff University (GB)
- University of Edinburgh (GB)
- Corresponding author
- Clarke, Toni-Kim
- ORCID
- Clarke, Toni-Kim
- Zeng, Yanni
- Navrady, Lauren
- Xia, Charley
- Haley, Chris
- Campbell, Archie
- Navarro, Pau
- Amador, Carmen
- Adams, Mark J.
- Howard, David M.
- Soler, Aleix
- Hayward, Caroline
- Thomson, Pippa A.
- Smith, Blair H.
- Padmanabhan, Sandosh
- Hocking, Lynne J.
- Hall, Lynsey S.
- Porteous, David J.
- Deary, Ian J.
- McIntosh, Andrew M.
- Venue
- Wellcome Open Research
- Publisher
- F1000 Research Ltd
- Published
- 2018-02-14
- Volume
- 3
- Pages
- 11
- ISSN
- 2398-502X (ISSN-L)
- PMC
- PMC6352921
- OpenAlex
- W3148329018
- Cited by
- 16
- References
- 50
- Citations by year
- 2026: 1 · 2024: 2 · 2023: 1 · 2022: 2 · 2021: 3 · 2020: 2 · 2019: 5
- FWCI
- 1.53
- Type
- journal article
- Language
- en
- Update notices
- new_version (2019-01-14)
- Open access
- gold
- doi.org
- Locations
- Wellcome Open Research (publishedVersion, cc-by)
- bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion)
- Discovery Research Portal (University of Dundee) (submittedVersion, cc-by)
- Edinburgh Research Explorer (University of Edinburgh) (submittedVersion, other-oa)
- Funders
- Medical Research Council (MC_PC_U127592696, MC_PC_U127561128)
- Dr. Mortimer and Theresa Sackler Foundation
- Biotechnology and Biological Sciences Research Council
- Scottish Funding Council (HR03006)
- Wellcome Trust (104036)
- Scottish Government Health Directorates (CZD/16/6)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetic Associations and Epidemiology
- Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neurotransmitter Receptor Influence on Behavior
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Mental Health Research Topics
- Keywords
- life events, major depressive disorder, neuroticism, heritability, genetic correlation, polygenic risk score, environmental risk factors, family-based genetic analysis
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.
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
