The DOI matches its Crossref record; 62 of the 63 references it cites were found in a registry or an index.
The Double-Edged Sword of Grandiose Narcissism: Implications for Successful and Unsuccessful Leadership Among U.S. Presidents
Abstract
Recent research and theorizing suggest that narcissism may predict both positive and negative leadership behaviors. We tested this hypothesis with data on the 42 U.S. presidents up to and including George W. Bush, using (a) expert-derived narcissism estimates, (b) independent historical surveys of presidential performance, and (c) largely or entirely objective indicators of presidential performance. Grandiose, but not vulnerable, narcissism was associated with superior overall greatness in an aggregate poll; it was also positively associated with public persuasiveness, crisis management, agenda setting, and allied behaviors, and with several objective indicators of performance, such as winning the popular vote and initiating legislation. Nevertheless, grandiose narcissism was also associated with several negative outcomes, including congressional impeachment resolutions and unethical behaviors. We found that presidents exhibit elevated levels of grandiose narcissism compared with the general population, and that presidents' grandiose narcissism has been rising over time. Our findings suggest that grandiose narcissism may be a double-edged sword in the leadership domain.
Overview
Integrity signals
Registry
Cites
Statistics
Verification
Claims the paper makes
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?
In the citing paper
“For example, narcissists promote bold visions and are charismatic, they tend to persist in the face of failure, and they are good in crisis management (Galvin et al., 2010; Watts et al., 2013).”
From Narcissistic Leaders and Their Victims: Followers Low on Self-Esteem and Low on Core Self-Evaluations Suffer Most (2018) · cites this paper as Watts et al., 2013
In the citing paper
“For example, narcissists promote bold visions and are charismatic, they tend to persist in the face of failure, and they are good in crisis management (Galvin et al., 2010; Watts et al., 2013).”
From Narcissistic Leaders and Their Victims: Followers Low on Self-Esteem and Low on Core Self-Evaluations Suffer Most (2018) · cites this paper as Watts et al., 2013
In the citing paper
“For example, narcissists promote bold visions and are charismatic, they tend to persist in the face of failure, and they are good in crisis management (Galvin et al., 2010; Watts et al., 2013).”
From Narcissistic Leaders and Their Victims: Followers Low on Self-Esteem and Low on Core Self-Evaluations Suffer Most (2018) · cites this paper as Watts et al., 2013
In the citing paper
“For example, narcissists promote bold visions and are charismatic, they tend to persist in the face of failure, and they are good in crisis management (Galvin et al., 2010; Watts et al., 2013).”
From Narcissistic Leaders and Their Victims: Followers Low on Self-Esteem and Low on Core Self-Evaluations Suffer Most (2018) · cites this paper as Watts et al., 2013
In the citing paper
“In political positions, narcissists’ tendency for risk taking may sometimes drive them to initiate bold legislative changes with relative disregard for the negative consequences these changes can bring about, as documented by research on narcissistic U.S. presidents’ political acts (Watts et al., 2013).”
From The "Why" and "How" of Narcissism: A Process Model of Narcissistic Status Pursuit (2020) · cites this paper as Watts et al., 2013
In the citing paper
“and may project themselves as goal achievers (Watts et al. 2013;Campbell et al. 2004).”
From Grandiose narcissism and performance in organizations: mediating role of subjective wellbeing (2020) · cites this paper as Watts et al. 2013
Citations
Cites
Diagnostic and Statistical Manual of Mental Disorders
American Psychiatric Association (2013) · doi:10.1176/appi.books.9780890425596 · Cited by 116,369
Diagnostic and Statistical Manual of Mental Disorders.
Widiger, T. A. (2000) · Oxford University Press eBooks · doi:10.1037/10518-009 · Cited by 19,766
Diagnostic and Statistical Manual of Mental Disorders, 5th ed.
Carter, M. J. (2014) · Therapeutic Recreation Journal · Cited by 15,154
Meta-Analytic Procedures for Social Research
Rosenthal, R. (1991) · doi:10.4135/9781412984997 · Cited by 4,635
Meta-Analytic Procedures for Social Research.
Metcalfe, A., & Rosenthal, R. (1994) · Journal of the Royal Statistical Society Series D (The Statistician) · doi:10.2307/2348600 · Cited by 4,249
McCrae, R. R., & Costa, P. T. (2010) · Medical Entomology and Zoology · Cited by 2,345
Raskin, R., & Terry, H. (1988) · Journal of Personality and Social Psychology · doi:10.1037/0022-3514.54.5.890 · Cited by 2,273
Raskin, R., & Terry, H. (1988) · Journal of Personality and Social Psychology · doi:10.1037//0022-3514.54.5.890 · Cited by 2,267
Encyclopedia of measurement and statistics
(2007) · Choice Reviews Online · doi:10.5860/choice.44-4214 · Cited by 1,389
Initial construction and validation of the Pathological Narcissism Inventory.
Pincus, A. L., Ansell, E. B., Pimentel, C. A., Cain, N. M., Wright, A. G. C., & Levy, K. N. (2009) · Psychological Assessment · doi:10.1037/a0016530 · Cited by 1,334
Flagged first, then by citations
1 of the 63 references couldn’t be matched to a known paper.
Research works printed but not linked: 6
- Blair C. A., 2006, Paper presented at the annual meeting of the Academy of Management
- Brown B., 2005, Otago Management Graduates Review, 3, 69
- Costa P. T., 1992, Revised NEO Personality Inventory (NEOPI-R) and NEO Five-Factor Inventory (NEO-FFI) professional manual
- Costa P. T., 2000, NEO PI-R professional manual
- Lilienfeld S. O., 2005, Psychopathic Personality Inventory-Revised professional manual
- Merry R. W., 2012, Where they stand: The American presidents in the eyes of voters and historians
Cited by
Sorted by citations
Items 101–200 of 204
Hyatt, C. S., Maples‐Keller, J. L., Sleep, C. E., Lynam, D. R., & Miller, J. D. (2018) · Journal of Research in Personality · doi:10.1016/j.jrp.2018.11.005 · Cited by 9
Introduction to the Dark Triad
Lyons, M. T. (2019) · Elsevier eBooks · doi:10.1016/b978-0-12-814291-2.00001-2 · Cited by 10
Williams, E. A., Pillai, R., McCombs, K. M., Lowe, K. B., & Deptula, B. J. (2020) · Leadership · doi:10.1177/1742715020902906 · Cited by 13
Tailab, M. M. K., BenYoussef, N., & Al‐Okaily, J. (2023) · Journal of financial reporting & accounting · doi:10.1108/jfra-06-2022-0224 · Cited by 12
Campbell, W. K., & Siedor, L. E. (2016) · Cambridge University Press eBooks · doi:10.1017/cbo9781316225608.010 · Cited by 8
The Personal Characteristics of Political Leaders: Quantitative Multiple-Case Assessments
Simonton, D. K. (2014) · Palgrave Macmillan US eBooks · doi:10.1057/9781137472038_4 · Cited by 8
Grandiose Narcissists Seek Status Selectively
Giacomin, M., Battaglini, A. M., & Rule, N. O. (2018) · Social Cognition · doi:10.1521/soco.2018.36.1.20 · Cited by 8
Grandiose narcissism and performance in organizations: mediating role of subjective wellbeing
Sakkar Sudha, K., & Shahnawaz, M. G. (2020) · Leadership, Education, Personality: An Interdisciplinary Journal · doi:10.1365/s42681-020-00015-0 · Cited by 7
Ozdenerol, E., Bingham-Byrne, R. M., & Seboly, J. D. (2023) · International Journal of Environmental Research and Public Health · doi:10.3390/ijerph20217023 · Cited by 10
Those Who Gift Only Themselves: An Analysis of Gifted Narcissists as Ultimate Self-Transactionalists
Desmet, O. A., & Sternberg, R. J. (2023) · Roeper Review · doi:10.1080/02783193.2023.2285042 · Cited by 6
Overview of the Impact of Psychopathy and Other Problematic Personality Constructs in the Workplace
Ray, S. J., & Fritzon, K. (2019) · Springer eBooks · doi:10.1007/978-3-030-27188-6_7 · Cited by 6
The impact of CEO narcissism and optimism on capital structure under pandemic conditions
Федорова, Е. А., Nevredinov, A., & Drogovoz, P. A. (2024) · Review of Behavioral Finance · doi:10.1108/rbf-04-2023-0087 · Cited by 6
Understanding and Coping in Social Relationships with Narcissists
Brunell, A. B., & Hermann, A. D. (2024) · Cambridge University Press eBooks · doi:10.1017/9781108908306 · Cited by 5
Accounting for the Horsemen of the Administrative Apocalypse
Fennimore, A. K., & Sementelli, A. J. (2018) · Public Integrity · doi:10.1080/10999922.2018.1443366 · Cited by 5
The Best Words: Linguistic Indicators of Grandiose Narcissism in Politics
Underberg, J. E., Gollwitzer, A., Oettingen, G., & Gollwitzer, P. M. (2019) · Journal of Language and Social Psychology · doi:10.1177/0261927x19883898 · Cited by 9
The Mental Well-Being of Politicians
Weinberg, A. (2022) · Cambridge University Press eBooks · doi:10.1017/9781108774871.009 · Cited by 4
Science advocacy in political rhetoric and actions
Quigley, M. C., & Silver, J. D. (2022) · Environment Systems & Decisions · doi:10.1007/s10669-022-09875-x · Cited by 4
Organizational Outcomes of Destructive Leadership: Summary and Evaluation
Karabatı, S. (2021) · Emerald Group Publishing Limited eBooks · doi:10.1108/978-1-80043-180-520211008 · Cited by 4
Wallis, J. (2021) · Global Society · doi:10.1080/13600826.2021.1942798 · Cited by 4
Wang, L., & Guo, Q. (2022) · Frontiers in Psychology · doi:10.3389/fpsyg.2022.858779 · Cited by 4
Gender and the Dark Side of Leadership
Eaton, A. A., & Nevicka, B. (2022) · Oxford University Press eBooks · doi:10.1093/oso/9780197552759.003.0010 · Cited by 4
Do we only have narcissists to choose from?
Sendinç, T., & Hatemi, P. (2023) · Electoral Studies · doi:10.1016/j.electstud.2023.102672 · Cited by 4
Czarna, A. Z., & Nevicka, B. (2019) · Springer eBooks · doi:10.1007/978-3-319-28099-8_2334-1 · Cited by 4
Radiation enterocolitis. A case report.
Heffernon, E. W., & Memik, F. (1969) · PubMed · Cited by 4
Braun, S. H. (2016) · Springer eBooks · doi:10.1007/978-3-319-31816-5_1900-1 · Cited by 4
Tatum, A. K., & Nai, A. (2022) · Research & Politics · doi:10.1177/20531680221145554 · Cited by 3
Dark Triad Personalities and Political Skill: Test and Amplification of Toxic Career Theory
Kückelhaus, B. P., & Blickle, G. (2024) · Springer studies on populism, identity politics and social justice · doi:10.1007/978-3-031-56415-4_10 · Cited by 3
Ren, F., Qiang, Y., Li, P., & Cheng, Z. (2024) · Current Psychology · doi:10.1007/s12144-024-06691-1 · Cited by 4
Zhang, A., Shi, X., Du, X., Miao, M., & Li, F. (2024) · Systems Research and Behavioral Science · doi:10.1002/sres.3077 · Cited by 4
Andino, M. V., Brown, M. F. D., Sturgeon, T., & Stanton, K. J. (2022) · Current Psychology · doi:10.1007/s12144-022-03851-z · Cited by 4
Wenn mehr Ganzheit gefordert wird – Agile Teams und ihre Personen
Csar, M., Bachmann, T., Bravo, K. Q., & Heemann, C. (2023) · Gruppe Interaktion Organisation Zeitschrift für Angewandte Organisationspsychologie (GIO) · doi:10.1007/s11612-023-00719-z · Cited by 3
Teflon leadership: crossing moral boundaries with impunity
Metz, R., & Kövesdi, V. (2026) · Frontiers in Political Science · doi:10.3389/fpos.2025.1606466 · Cited by 3
The Dark Triad in the Workplace
Lyons, M. T. (2019) · Elsevier eBooks · doi:10.1016/b978-0-12-814291-2.00006-1 · Cited by 4
Cavari, A., Yoel, B., & Lowenkamp, H. (2021) · American Politics Research · doi:10.1177/1532673x211022630 · Cited by 3
Surround yourself with creative people: How employee narcissism connects to creativity
Guo, Q. (2025) · Frontiers in Psychology · doi:10.3389/fpsyg.2025.1646817 · Cited by 2
Chen, N., Li, D., Lv, H., Zheng, C., & Zhao, X. (2025) · Journal of Business Research · doi:10.1016/j.jbusres.2025.115737 · Cited by 2
Self-Enhancing Self-Presentation
Sedikides, C., Hoorens, V., & Dufner, M. (2015) · Emerald Group Publishing Limited eBooks · doi:10.1108/978-1-68123-169-320251003 · Cited by 29
The effects of self-other rating agreement on ethical behavior: an experimental investigation
Kass, D., Kim, J. S., Zhu, W., & Erdley, S. D. (2021) · International Journal of Organization Theory and Behavior · doi:10.1108/ijotb-08-2020-0145 · Cited by 2
Liu, Z., Zhang, X., Xu, H., Deng, H., Li, J., & Lan, Y. (2022) · Frontiers in Psychology · doi:10.3389/fpsyg.2022.938864 · Cited by 3
Narcyzm i sprawstwo w kulturze artystycznej
Dziadzia, B. (2022) · Humaniora · doi:10.14746/h.2022.4.4 · Cited by 2
Automated question answering for unveiling leadership dynamics in U.S. Presidential speeches
Rybinski, K. I. (2024) · Expert Systems with Applications · doi:10.1016/j.eswa.2024.125222 · Cited by 4
Jacobs, A. J. (2022) · Global Discourse · doi:10.1332/204378921x16281926170803 · Cited by 2
Reverse Engineering From Eminent Exemplars: How About a Retrospective Study Too?
Simonton, D. K. (2017) · Roeper Review · doi:10.1080/02783193.2017.1318997 · Cited by 2
Kurtulmuş, B. E. (2017) · Palgrave Macmillan UK eBooks · doi:10.1057/978-1-137-57940-9_6 · Cited by 2
Lenzenweger, M. F., Patrick, C. J., Watts, A. L., Latzman, R. D., & Depue, R. A. (2022) · Clinical Psychological Science · doi:10.1177/21677026221125684 · Cited by 4
Physician Leader, Humble Thyself: Balancing Narcissism and Humility in Healthcare Leadership
Sherrer, D. M., Fischer, N. A., & McCombs, K. M. (2023) · Southern Medical Journal · doi:10.14423/smj.0000000000001594 · Cited by 2
Al‐Shammari, M. (2017) · UTA ResearchCommons (University of Texas Arlington) · Cited by 2
Leadership Personality Characteristics and Foreign Policy
Winter, D. G. (2019) · doi:10.1093/obo/9780199743292-0256 · Cited by 2
Czarna, A. Z., & Nevicka, B. (2020) · Springer eBooks · doi:10.1007/978-3-319-24612-3_2334 · Cited by 2
The Development of a Measure of Dark Triad Traits in a Corporate Sample
Fritzon, K. (2019) · Springer eBooks · doi:10.1007/978-3-030-27188-6_8 · Cited by 1
The United States of Trump Corp.: The ‘Not Normal/New Normal’ Governing Style of a Personal Brand
Crombez, J. M., & Panageotou, S. (2020) · Fast Capitalism · doi:10.32855/fcapital.202001.003 · Cited by 1
Birkenmaier, L., & Lechner, C. M. (2025) · Political Analysis · doi:10.1017/pan.2025.10025 · Cited by 3
Bright systems, dark traits: High-performance work systems amplify narcissistic managers' derailment
Agarwal, P., & Farndale, E. (2026) · Personality and Individual Differences · doi:10.1016/j.paid.2026.113700 · Cited by 1
How Reliable Are Personality Judgments by Political Experts? The Curious Case of Donald Trump
Joly, J., & Hofmans, J. (2023) · Personality Science · doi:10.5964/ps.6715 · Cited by 1
Self-presentation of the US presidential candidates in 2016 and 2020
Diedkova, G. (2024) · Language and Dialogue · doi:10.1075/ld.00163.die · Cited by 1
Test-Retest Reliability of the Political Elites Aversive Personality Scale (PEAPS)
Maier, J., Oschatz, C., Dian, M., & Zettler, I. (2024) · Studia Psychologica Theoria et praxis · doi:10.21697/sp.2024.24.1.03 · Cited by 1
Do Narcissist Phubs or Get Phubbed? Analyzing the Role of Motivational Systems
Sudha, K. S., Shahnawaz, M. G., & Hasan, Z. (2024) · The Journal of Psychology · doi:10.1080/00223980.2024.2363538 · Cited by 1
(Don't) fear the bad leader: three influential myths about bad leadership
Metz, R. (2025) · Frontiers in Political Science · doi:10.3389/fpos.2025.1589496 · Cited by 3
Development of the Academic Harassment Tendency Scale for Science Academia
Yamazaki, Y., Nomura, K., Sato, K., Nohara, M., Kataoka, H. U., Okubo, Y., Karita, K., Heima, M., Shimizu, I., Kitano, N., et al. (2025) · Journal of Academic Ethics · doi:10.1007/s10805-025-09662-8 · Cited by 1
Smith, A. J., Graña, J., Bitterlich, N., Bhugra, D. K., Guttormsen, S., & Liebrenz, M. (2025) · International Review of Psychiatry · doi:10.1080/09540261.2025.2596930 · Cited by 1
Die „dunkle Seite“ der Führung
Kuhn, T. S., & Weibler, J. (2022) · Fehlzeiten-Report · doi:10.1007/978-3-662-65598-6_14 · Cited by 1
Dark Personality Features and Employment
Czarna, A. Z., & Zajas, A. (2020) · Springer eBooks · doi:10.1007/978-3-319-24612-3_2094 · Cited by 2
Braun, S. H. (2018) · Springer eBooks · doi:10.1007/978-3-319-20928-9_1900 · Cited by 1
Krispenz, A., & Bertrams, A. (2023) · SSRN Electronic Journal · doi:10.2139/ssrn.4560799 · Cited by 1
Benning, S. D., Barchard, K. A., & Westfall, R. S. (2023) · PsyArXiv (OSF Preprints) · doi:10.31234/osf.io/8qbgd · Cited by 1
The role of narcissism in sport coaching: a self-determination theory perspective
Matošić, D. (2017) · University of Birmingham Institutional Research Archive (University of Birmingham)
Dark Personality Features and Employment
Czarna, A. Z., & Zajas, A. (2018) · Springer eBooks · doi:10.1007/978-3-319-28099-8_2094-1 · Cited by 1
Die ganze Welt dreht sich um mich – Narzissmus im Internet
Tränkner, J. (2019) · PiD - Psychotherapie im Dialog · doi:10.1055/a-0771-7322
Kranefeld, I., Genau, H. A., & Blickle, G. (2021) · Persönlichkeit und weltpolitische Gestaltung · doi:10.1007/978-3-658-32348-6_5
Timber! How Loss of Trust Contributes to the Downfall of Narcissistic Leaders
Lynch, J. (2021) · Scholarship@Western (Western University)
Weinberg, A. (2022) · Cambridge University Press eBooks · doi:10.1017/9781108774871.003
(2019) · Elsevier eBooks · doi:10.1016/b978-0-12-814291-2.10000-2
Braun, S. H. (2022) · Springer eBooks · doi:10.1007/978-3-030-66252-3_1900 · Cited by 1
Dian, M. (2024) · Party Politics · doi:10.1177/13540688241234516 · Cited by 1
Birkenmaier, L., & Lechner, C. M. (2025) · OSF Preprints (OSF Preprints) · doi:10.31219/osf.io/7nhjz_v1
Birkenmaier, L., & Lechner, C. M. (2025) · OSF Preprints (OSF Preprints) · doi:10.31219/osf.io/7nhjz_v2
SANTANA, C. M., Flores-Mendoza, C. E., Martín, S. E., Herrero, Ó., & Marañón, R. C. (2025) · SSRN Electronic Journal · doi:10.2139/ssrn.5388475
Can narcissistic managers fake that they care?
Hamstra, M. R. W. (2021) · doi:10.64628/aak.fwywxfhh9
Maier, J., & Nai, A. (2025) · Acta Psychologica · doi:10.1016/j.actpsy.2025.105578
van de Wardt, M., Bundi, P., Loewen, P. J., Rasmussen, A., Sheffer, L., & Varone, F. (2025) · European Journal of Political Research · doi:10.1017/s1475676525100224 · Cited by 1
Hart, W., Hall, B. T., & Roberts, B. C. (2026) · Personality and Individual Differences · doi:10.1016/j.paid.2026.113725
Zoizner, A., Nai, A., & Maier, J. (2026) · Journalism & Mass Communication Quarterly · doi:10.1177/10776990261436064
Pourquoi le pouvoir change la personnalité
Josse, É. (2026) · HEGEL - HEpato-GastroEntérologie Libérale · doi:10.3917/heg.161.0126
Dúbravská, S., & Haľama, P. (2026) · Pastoral Psychology · doi:10.1007/s11089-026-01332-9
Winter, D. G. (2026) · doi:10.1093/9780197648759.003.0006
Winter, D. G. (2026) · doi:10.1093/9780197648759.002.0005
Winter, D. G. (2026) · doi:10.1093/9780197648759.002.0008
Winter, D. G. (2026) · doi:10.1093/9780197648759.003.0002
Why Study Political Leaders at a Distance?
Winter, D. G. (2026) · doi:10.1093/9780197648759.003.0001
Winter, D. G. (2026) · doi:10.1093/9780197648759.002.0006
Winter, D. G. (2026) · doi:10.1093/9780197648759.003.0003
Winter, D. G. (2026) · doi:10.1093/9780197648759.002.0007
Winter, D. G. (2026) · doi:10.1093/9780197648759.005.0004
Outline of Responsibility Scoring System
Winter, D. G. (2026) · doi:10.1093/9780197648759.005.0003
Studies Using At-a-Distance Scoring of Implicit Motives
Winter, D. G. (2026) · doi:10.1093/9780197648759.005.0007
Winter, D. G. (2026) · doi:10.1093/9780197648759.003.0004
Political Leaders at a Distance
Winter, D. G. (2026) · doi:10.1093/9780197648759.001.0001
Metadata
- Authors
- Watts, A. L., Lilienfeld, S. O., Smith, S. F., Miller, J. D., Campbell, W. K., Waldman, I. D., Rubenzer, S. J., & Faschingbauer, T. J.
- Affiliations
- Emory University (US)
- University of Georgia (US)
- Concord, New Hampshire
- Foundation for the Study of Personality in History, Houston, Texas
- Corresponding author
- Watts, Ashley L.
- ORCID
- Venue
- Psychological Science
- Publisher
- SAGE Publications
- Published
- 2013-10-08
- Volume
- 24
- Issue
- 12
- Pages
- 2379-2389
- ISSN
- 0956-7976 (ISSN-L)
- 1467-9280
- OpenAlex
- W2107485453
- Cited by
- 206
- References
- 63
- Citations by year
- 2026: 24 · 2025: 13 · 2024: 15 · 2023: 12 · 2022: 22 · 2021: 18 · 2020: 19 · 2019: 23 · 2018: 20 · 2017: 16 · 2016: 11 · 2015: 8 · 2014: 4
- FWCI
- 8.45
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Psychological Science (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Social Sciences › Psychology › Clinical Psychology › Personality Traits and Psychology
- Social Sciences › Political Science and International Relations › History, Medicine, and Leadership
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Evolutionary Psychology and Human Behavior
- Keywords
- grandiose narcissism, vulnerable narcissism, presidential leadership, American presidents, leadership behavior, presidential performance, crisis management, agenda setting, impeachment, unethical behavior
- MeSH terms
- Aged, Famous Persons, Humans, Leadership, Male, Middle Aged, Narcissism, Personality, Politics, Task Performance and Analysis, United States
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