Associations among disability, depression, anxiety, stress, and quality of life between stroke survivors and their family caregivers: An Actor‐Partner Interdependence Model
Abstract
Aim To explore the effects of disability, depressive, anxiety and stress symptoms on patients' and their partners' quality of life (QoL) using the actor-partner interdependence model (APIM). Design A cross-sectional study using actor-partner interdependence model. Methods We recruited 183 dyads of stroke survivors and their family caregivers in Indonesia. The World Health Organization Disability Assessment (WHODAS 2.0), Depression, Anxiety and Stress (DASS-42) and Rand Short Form Health Survey (SF-36) were used to measure disability, depressive, anxiety and stress symptoms and QoL of stroke survivors and family caregivers. The actor-partner interdependence model was tested using multilevel modelling. The actor-partner interdependence mediation model (APIMeM) was applied to estimate the direct and indirect effect. Results Disability had actor effects on stroke survivor's overall QoL and partner effect on family caregiver's overall QoL. More severe disability of stroke survivors was associated with a lower overall QoL of their own and that of family caregiver's overall QoL. Depressive symptoms of stroke survivors had actor effects on stroke survivors' overall QoL and partner effects on family caregivers' overall QoL. Actor and partner effects also exist on family caregiver's depression symptoms to their own overall QoL and stroke survivor's overall QoL. Moreover, higher anxiety symptoms were associated with lower levels of their own and partner's overall QoL in both stroke surv…
Integrity signals
Registry
Cites
Statistics
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?
There is a substantial association between post-stroke anxiety and psychological flexibility in stroke patients.
“There is a substantial association between post-stroke anxiety and psychological flexibility in stroke patients, which also affects their quality of life and mental quality (Lv et al. 2021;Stahl et al. 2024;Yuliana et al. 2023).”
From The Relationship Between Knowledge, Psychological Flexibility, Anxiety and Healthy Behaviour in Stroke Patients: A Chain Mediation Model. (2026) · cites this paper as Yuliana et al. 2023
Post-stroke anxiety and psychological flexibility affect quality of life and mental quality in stroke patients.
“There is a substantial association between post-stroke anxiety and psychological flexibility in stroke patients, which also affects their quality of life and mental quality (Lv et al. 2021;Stahl et al. 2024;Yuliana et al. 2023).”
From The Relationship Between Knowledge, Psychological Flexibility, Anxiety and Healthy Behaviour in Stroke Patients: A Chain Mediation Model. (2026) · cites this paper as Yuliana et al. 2023
Cites
Physical and mental health effects of family caregiving
Schulz, R., & Sherwood, P. R. (2008) · AJN, American Journal of Nursing · doi:10.1097/01.naj.0000336406.45248.4c · Cited by 1,375 · see citing works
Depression, activities of daily living and quality of life in patients with stroke
Haghgoo, H. A., Pazuki, E. S., Hosseini, A. S., & Rassafiani, M. (2013) · Journal of the Neurological Sciences · doi:10.1016/j.jns.2013.02.027 · Cited by 152 · see citing works
Anticipatory grief of spousal and adult children caregivers of people with dementia
Cheung, D. S. K., Ho, K. H. M., Cheung, T. F., Lam, S. C., & Tse, M. M. Y. (2018) · BMC Palliative Care · doi:10.1186/s12904-018-0376-3 · Cited by 75 · see citing works
Flagged first, then by citations
Cited by
Sorted by citations
Caregiver burden after stroke: a 10-year follow-up study of Polish caregivers for stroke patients
Jaracz, K., Grabowska-Fudala, B., Jaracz, J., Moczko, J., Kleka, P., Pawlicka, A., & Górna, K. (2024) · BMC Nursing · doi:10.1186/s12912-024-02251-x · Cited by 30 · see citing works
“The consequences of stroke affect not only patients but also their loved ones, usually family members, who take over the care responsibilities after the hospital discharge [14].”
BackgroundAl-Shaer, E., Aliedan, M. M., Zayed, M. A., Elrayah, M., & Moustafa, M. A. (2024) · Sustainability · doi:10.3390/su16020644 · Cited by 25 · see citing works
Feng, G., Weng, F., Lu, W. P., Xu, L., Zhu, W., Tan, M., & Weng, P. (2025) · International Journal of General Medicine · doi:10.2147/ijgm.s516247 · Cited by 28 · see citing works
“Dilemma of insufficient family support: 28,29 Against the backdrop of the “four-two-one” family structure and empty nesters, the problem of insufficient family support has become increasingly prominent.”
Zrelak, P., Seagraves, K. B., Belagaje, S. R., Dusenbury, W., García, J. J., Hadidi, N. N., Keigher, K., Love, M., Pucciarelli, G., Schorr, E. N., et al. (2024) · Stroke · doi:10.1161/str.0000000000000471 · Cited by 15 · see citing works
“16,36,39,40 Approximately one-third of those with poststroke anxiety will have had a prestroke mood or anxiety disorder.”
Eriku, G. A., Bekele, G., Yitayal, M. M., Belete, Y., & Girma, Y. (2023) · Neuropsychiatric Disease and Treatment · doi:10.2147/ndt.s418074 · Cited by 11 · see citing works
“The stroke survivor’s disability and depressive symptoms affect the quality of life of the survivor and their caregivers.(12) It was reported that the burden of depression among caregivers of stroke survivors ranges from 23% to 57%, and its global pooled prevalence is 40.”
BackgroundMonjezi, A., Karampourian, A., Khazaei, S., & Khazaei, M. (2025) · Aging Clinical and Experimental Research · doi:10.1007/s40520-025-03096-3 · Cited by 8
Tsai, S.-J., Li, C.-C., & Pai, H.-C. (2024) · International Journal of Nursing Practice · doi:10.1111/ijn.13257 · Cited by 7
He, Y., Huang, Z.-M., Deng, H., Huang, J., Wu, J.-H., & Wu, J.-S. (2023) · European Journal of Physical and Rehabilitation Medicine · doi:10.23736/s1973-9087.23.08018-8 · Cited by 7 · see citing works
Assessment of Skills of Caregivers Providing Care for Stroke Patients in East Kazakhstan Region
Kairatova, G., Khismetova, Z., Smailova, D., Serikova-Esengeldina, D., Berikuly, D., Akhmetova, K., & Shalgumbayeva, G. (2024) · Healthcare · doi:10.3390/healthcare13010027 · Cited by 6
“The early detection of this condition using screening tools with high diagnostic accuracy is critically important [13,14].”
Moustafa, M. A., Elshaer, I. A., Aliedan, M. M., Zayed, M. A., & Elrayah, M. (2024) · Journal of Disability Research · doi:10.57197/jdr-2024-0013 · Cited by 4 · see citing works
“The connection between stress experienced by students and a range of adverse consequences, encompassing both the general QOL and the state of welfare pertaining to health, has been established (Yuliana et al., 2023).”
BackgroundResultInfluentialCai, H., Cai, S., Li, A., & Guo, A.-S. (2025) · Frontiers in Neurology · doi:10.3389/fneur.2025.1526506 · Cited by 5 · see citing works
Liu, B., An, J., Wang, H., Mei, Y.-X., Lin, B.-L., Song, W., Zhang, Z.-X., & Wang, W.-N. (2025) · Journal of Clinical Nursing · doi:10.1111/jocn.17720 · Cited by 5 · see citing works
Shi, Y., Chong, M. S., Wang, W., Li, X., Zhang, W., Lin, B., Zhang, Z., & Mei, Y. (2025) · Nursing and Health Sciences · doi:10.1111/nhs.70040 · Cited by 5 · see citing works
Liu, Y., Wei, Z., Jing, L., Sui, Z., Fu, P., Chen, X., & Yu, G.-L. (2025) · Quality of Life Research · doi:10.1007/s11136-025-03991-2 · Cited by 4 · see citing works
“…has suggested that individuals who engage in more DC (e.g., stress communication with their partners) tend to perceive greater emotional support and care from their partners, which could alleviate negative emotions and promote health behaviors (e.g., health diet) linked to physical QoL [36–38].”
Zhang, Z., Dong, Y., & Sun, Y. (2025) · Medicine · doi:10.1097/md.0000000000042570 · Cited by 4 · see citing works
STROKE AND ITS IMPACT ON FAMILIES OF PATIENTS: A CROSS-SECTIONAL SURVEY OF FAMILY MEMBERS
Assylbek, M. I., Anartaуeva, M., Zharkynbekova, N., & Kemelbekov, K. (2025) · Central Asian Journal of Medical Hypotheses and Ethics · doi:10.47316/cajmhe.2025.6.1.04 · Cited by 4 · see citing works
Ma, R., Qiao, M., Zhou, Y., Sun, W., Lv, Y., Zhou, X., Wang, Y., Wu, X., & Yu, R. (2026) · Journal of Clinical Nursing · doi:10.1111/jocn.17820 · Cited by 3 · see citing works
Jiang, Y.-P., & Wang, L. (2025) · Journal of Multidisciplinary Healthcare · doi:10.2147/jmdh.s552868 · Cited by 3 · see citing works
Xu, C., Qian, L., Qiu, Y.-H., Ye, F., Hao, J., Wang, J., & Qiu, Y.-Y. (2025) · Journal of Psychosomatic Research · doi:10.1016/j.jpsychores.2025.112144 · Cited by 3 · see citing works
Khan, E. E. A., Arifin, W. N., & Musa, K. I. (2024) · Cureus · doi:10.7759/cureus.64160 · Cited by 2 · see citing works
“A lower patients' dependency level is postulated to be linked with a lesser burden for caregivers, which in turn will improve the caregivers' QoL [5].”
BackgroundInfluentialKylén, M., Sturge, J., Lipson-Smith, R., Schmidt, S. M., Pessah-Rasmussen, H., Svensson, T., de Vries, L., Bernhardt, J., & Elf, M. (2023) · JMIR Research Protocols · doi:10.2196/52489 · Cited by 3 · see citing works
“The effects of stroke can be profound and lead to a range of activity and participation limitations [9-11], such as reduced quality of life, social isolation [12-14], and adverse events such as falls [9,15].”
BackgroundYuan, H., You, J., Huang, J., Zhao, W., Jin, X., & Xu, W. (2026) · BMC Psychology · doi:10.1186/s40359-026-04497-3 · Cited by 2 · see citing works
“Drawing upon the Systemic Transactional Model [24]and the Actor–Partner Interdependence Mediation Model and [39], we propose that positive dyadic coping enhances each partner’s perception of relational support, emotional closeness, and mutual responsiveness.”
Infortuna, C., Buccafusca, M., Graceffa, A., Maiorana, E., Wang, R., Ganesh, S., Yedidia, O., Bruno, A., Iannuzzo, F., Thomas, F. P., et al. (2025) · Frontiers in Neurology · doi:10.3389/fneur.2025.1561995 · Cited by 2 · see citing works
Sun, Q., Wang, S.-S., Song, W., Ge, S., Li, X., Ma, L., Zhang, Z., & Mei, Y.-X. (2025) · Journal of Nursing Scholarship · doi:10.1111/jnu.70023 · Cited by 2 · see citing works
Nomogram combined neuron-specific enolase and NIHSS for prediction of post stroke depression
Yan, C.-M., Zheng, W.-C., Si, T., Huang, L.-Y., Wen, L.-L., Shen, H.-X., & Qu, M. (2025) · International Journal of Neuroscience · doi:10.1080/00207454.2025.2488758 · Cited by 2 · see citing works
Association of Vitamin B12 and Polymorphism of TCN2 with Early-Onset Post-Stroke Depression
Zhang, J.-Y., Liao, Q., Chen, H., Liu, F., Sun, D.-R., Luo, S., Xiao, Y., Xu, W.-Y., Tian, F., & Song, M. (2024) · Neuropsychiatric Disease and Treatment · doi:10.2147/ndt.s480417 · Cited by 2 · see citing works
Wang, Y., Qiu, X.-K., Zhang, Y., Li, R., Sun, Z., & Li, Q.-P. (2024) · Seminars in Oncology Nursing · doi:10.1016/j.soncn.2024.151717 · Cited by 2 · see citing works
Morris, M., Atterbury, E., Minichetti, C., Santos, N., Farrell, A., Hanel, A. N., Porras, M., Leak, K., Tepper, L., Whalen, S., et al. (2023) · Journal of Dental Education · doi:10.1002/jdd.13343 · Cited by 2 · see citing works
Understanding the process of becoming a family caregiver for stroke survivors
Fonseca-Mardones, I., & Hernández-Lanas, O. (2025) · Cadernos Brasileiros de Terapia Ocupacional · doi:10.1590/2526-8910.cto401339122 · Cited by 2 · see citing works
Xu, F.-L., Mei, S., Yang, L.-N., Zhai, D.-H., Xu, Y.-H., Gui, T.-T., & Yan, N. (2026) · Journal of clinical neuroscience · doi:10.1016/j.jocn.2026.111953 · Cited by 1
Liu, Z., Li, Y.-H., Fang, Y., Wang, H., Wu, T., Liu, S., Yang, Y.-M., Qin, Y.-Y., Tao, X.-G., Mao, J., et al. (2026) · Frontiers in Neurology · doi:10.3389/fneur.2025.1737297 · Cited by 1 · see citing works
Zhang, L., Zhang, X., Tang, W., Wang, Q., Zou, L., Zhou, L., & Chen, Y. (2025) · Renal Failure · doi:10.1080/0886022x.2025.2612439 · Cited by 4 · see citing works
“Building on this evidence, studies of chronic disease dyads consistently demonstrate bidirectional burden transmission [12,13].”
Latent Profile Analysis of Dyadic Decision Self-Efficacy Among Stroke Patients and Their Caregivers.
Shi, Y., Chong, M.-S., Mei, Y.-X., Zhang, Z., Liu, Y.-T., Zhang, S., Lin, B.-L., Chen, S.-Y., & Li, X. (2025) · Journal of Clinical Nursing · doi:10.1111/jocn.70061 · Cited by 1 · see citing works
Xu, R., Ma, G., Hua, L., Liu, Y., Mu, T., & Chen, D. (2025) · American Journal of Preventive Medicine · doi:10.1016/j.amepre.2025.107734 · Cited by 2 · see citing works
Benefit Finding Among Caregivers With Stroke: A Cross-Sectional Study.
Yue, J., Huang, X.-Y., Liu, S., Liu, Y., Li, Y., Chen, L., & Li, R. (2025) · Nursing and Health Sciences · doi:10.1111/nhs.70019 · Cited by 1 · see citing works
What are 'emerging methodologies' in nursing research? Our perspectives as early career researchers.
Smith, J. G., & Tobiano, G. (2023) · Journal of Advanced Nursing · doi:10.1111/jan.15876 · Cited by 1
Zhu, S.-S., Ban, N., Miao, X., Guo, M., & Ma, L. (2026) · Frontiers in Public Health · doi:10.3389/fpubh.2026.1890113
“Studies indicate (7, 8) that the incidence of depression ranges from 9% to 21% within 3 months to 1 year after a stroke, with a cumulative incidence ranging from 21% to 55% within the first year.”
Wang, W., Fu, Y.-N., Xu, H.-N., Dong, Z.-Z., & Shi, Y.-K. (2026) · Patient Preference and Adherence · doi:10.2147/ppa.s641058
Wu, Y., Liu, C., Wu, Y.-H., Ji, D.-F., Sun, Y., & Dai, R.-F. (2026) · Frontiers in Public Health · doi:10.3389/fpubh.2026.1910517
“The Actor–Partner interdependence model breaks through the traditional individualistic research paradigm and emphasizes that in intimate relationships, the outcome variables of individuals are affected by both their own predictors and their partner’s predictors (12).”
Zou, W.-J., Zhou, W., Li, J., Xie, Z.-R., & Liao, C.-L. (2026) · Geriatric Nursing · doi:10.1016/j.gerinurse.2026.104320
Isidoro-Cabañas, E., & Pérez-Mármol, J. M. (2026) · Adapted Physical Activity Quarterly · doi:10.1123/apaq.2025-0146
Zhang, Y.-Y., Wang, Y.-L., Hao, Y., Li, Y., Ma, B.-X., Yang, J., Zheng, J., Zhang, X., Wang, Y.-G., Lin, M., et al. (2026) · Clinical Rehabilitation · doi:10.1177/02692155261478022
Callaghan, R., Dalton, K., Coffey, F., Foley, T., Moloney, R., Waeber, C., & Hartigan, I. (2026) · Journal of Affective Disorders Reports · doi:10.1016/j.jadr.2026.101148
Cao, X., Chen, R., Qu, Y., Ban, Y., & Zhang, Q. (2026) · Psychological Medicine · doi:10.1017/s0033291726105273
“In addition, our research findings indicated that family therapy was more effective than TAU in alleviating mild PSD. Research indicated that PSD was associated with an individual ’ s family system (Yuliana et al., 2023).”
Zhu, L.-L., Han, H., Wang, H., Xie, J.-R., Cheng, X., Song, W., Huang, L., & Zhang, H. (2026) · Frontiers in Psychiatry · doi:10.3389/fpsyt.2026.1826436
“The Actor-Partner Interdependence Model (APIM) posits that interactions between individuals in a close relationship affect both their own and their partner ’ s outcomes (21).”
Arslan, Ö. B., Evleksiz, T., & Akyurek, G. (2026) · OTJR: Occupation, Participation and Health · doi:10.1177/15394492261431564
Kylén, M., Johansson, M. F., McCarthy, L., Meijering, L., Tomsone, S., Tistad, M., & Elf, M. (2026) · BMJ Open · doi:10.1136/bmjopen-2025-110976
Cheng, S.-C., Gao, G., Guo, Y., Xiao, Y., Li, L., & Yu, X.-D. (2026) · Scientific Reports · doi:10.1038/s41598-026-45452-x
“Negative emotions such as depression and anxiety may further weaken self-efficacy beliefs, potentially creating a vicious cycle, as suggested by Yuliana et al. 18 in their study of stroke survivor–caregiver dyads.”
Family Caregivers Challenges for Stroke Survivors in the Community: A Literature Review
Israfil, I., Wulandari, S., Suyasa, I., Indrayani, N. L. D., & Agustini, N. I. B. (2026) · MEDICA (International Medical Scientific Journal) · doi:10.53770/medica.v8i3.843
“Effective solutions include comprehensive psychosocial support interventions for both patients and family caregivers to reduce burden, enhance well-being, and improve overall care quality (Yuliana et al., 2023), as well as the development of homecare services (Paryono et al., 2022).”
Li, R., Wu, Y., Wang, Y., Li, Y., & Song, H. (2026) · Patient Preference and Adherence · doi:10.2147/ppa.s573364
“9,10 Therefore, this study employs a cross-lagged analysis within the actor-partner interdependence model (APIM) framework to longitudinally examine the developmental trajectories and bidirectional predictive relationships between family resilience and fear of disease recurrence in elderly patients…”
Liu, Z., Xiang, D., Zhang, Z., Lin, B., Chen, S., Li, X., & Mei, Y. (2026) · International Journal of Nursing Practice · doi:10.1111/ijn.70133
Huang, C.-H., Shi, F.-H., Yang, X.-Y., Liu, S.-F., Zhou, Y.-J., & Li, X.-M. (2026) · Journal of the International Association of Providers of AIDS Care · doi:10.1177/23259582261440323
Hou, H., Luo, D., Zhu, S.-Z., Zhou, S.-C., Yan, S.-Y., Jiang, Y., Wang, X.-Q., Liu, Q., Zou, H.-J., & Yang, B.-X. (2026) · Depression and Anxiety · doi:10.1155/da/6987736
Normalia, N., Irwan, A. M., Setyawati, A., & Aziz, N. A. (2025) · Gulhane Medical Journal · doi:10.4274/gulhane.galenos.2025.78790
Liu, Y.-T., Xiang, D., Ge, S., Wang, S.-S., Xie, J.-F., Liu, Z., Zhang, S.-X., Zhang, Z., Chen, S.-Y., Li, X., et al. (2025) · Nursing Reports · doi:10.3390/nursrep15100372
“This sudden caregiving role shift can increase the risk of depressive symptoms, with a reported prevalence of 53.9% among spousal caregivers [11].”
InfluentialKimura, D., Bizen, H., Kunoh, K., Nakashima, D., & Iituka, T. (2025) · Cureus · doi:10.7759/cureus.95111
“Furthermore, patients' ADL impairment indirectly affects caregivers' mental health and well-being by increasing depression, anxiety, and stress [27,28].”
Biopsychosocial Needs and Quality of Life for Patients with Hemiplegia
Mohamed, R., Ali, Z. H., & Elkattan, B. A. E. (2025) · Helwan International Journal for Nursing Research and Practice · doi:10.21608/hijnrp.2025.404629.1388
“Also, Yuliana, et al., (2023), in a study titled “Associations among disability, depression, anxiety, stress, and quality of life between stroke survivors and their family caregivers” that one third of subject study had depression.”
The Impact of the Severe Consequences of a Stroke on Family Members Providing Care
Assylbek, M. I., Mariya, A., Nazira, Z., Marina, I., Kanatzhan, K., Bibigul, D., Gulzat, S., & Aizat, S. (2025) · Bangladesh Journal of Medical Science · doi:10.3329/bjms.v24i2.81552
“Furthermore, it indirectly reduces both physical (PCS) and mental quality of life (MCS) for stroke survivors and their family caregivers through symptoms of depression, anxiety, and stress 10,11 .”
Shrivastava, S., Bobhate, P., & Mishra, V. (2025) · International journal of Nutrition Pharmacology Neurological Diseases · doi:10.4103/ijnpnd.ijnpnd_162_24
Guo, S.-J., Qin, Q.-R., Zhang, H., Shi, H., & Zhang, Q.-F. (2024) · Journal of Clinical Nursing · doi:10.1111/jocn.17555
Zhang, X., Dai, J., Chen, Y., Yang, Y., Yang, L., & Li, W. (2024) · Current Psychology · doi:10.1007/s12144-024-05807-x · Cited by 1 · see citing works
Experiences of Caring for Adults with Acquired Physical Disabilities: A Qualitative Study
Mohamad, N. B. Z., Tan, G. Y. Q., & Asano, M. (2026) · Journal of long-term care · doi:10.31389/jltc.373
Fonseca-Mardones, I., & Hernández-Lanas, O. (2025) · Cadernos Brasileiros de Terapia Ocupacional · doi:10.1590/2526-8910.cto401339123
- Authors
- Yuliana, S., Yu, E., Rias, Y. A., Atikah, N., Chang, H. J., & Tsai, H. T.
- Affiliations
- Sekolah Tinggi Ilmu Kesehatan Yahya Bima (ID)
- The University of Texas Health Science Center at Houston (US)
- Institut Ilmu Kesehatan Bhakti Wiyata (ID)
- Politeknik Kesehatan Kemenkes Surakarta (ID)
- National Yang Ming Chiao Tung University (TW)
- Taipei Medical University (TW)
- Corresponding author
- Tsai, Hsiu Ting
- Venue
- Journal of Advanced Nursing
- Publisher
- Wiley
- Published
- 2022-10-18
- Volume
- 79
- Issue
- 1
- Pages
- 135-148
- ISSN
- 0309-2402 (ISSN-L)
- 1365-2648
- OpenAlex
- W4306742563
- Cited by
- 71
- References
- 0
- Citations by year
- 2026: 22 · 2025: 26 · 2024: 15 · 2023: 7 · 2022: 1
- FWCI
- 5.29
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of Advanced Nursing (publishedVersion)
- PubMed (publishedVersion)
- Funders
- Ministry of Science and Technology, Taiwan (MOST109‐2314‐B‐038‐110‐, MOST110‐2314‐B‐038‐081)
- Topics
- Health Sciences › Medicine › Rehabilitation › Stroke Rehabilitation and Recovery
- Health Sciences › Health Professions › Pharmacy › Nursing care and research
- Health Sciences › Medicine › Oncology › Cancer survivorship and care
- Keywords
- stroke, family caregivers, quality of life, disability, depression, anxiety, stress, actor-partner interdependence, dyads, mediation, caregiver burden, WHODAS 2.0, DASS-42, SF-36, Indonesia
- MeSH terms
- Anxiety, Cross-Sectional Studies, Depression, Humans, Quality of Life, Caregivers, Survivors, Stroke
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
