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PubMed2001

Proxy reliability: health-related quality of life (HRQoL) measures for people with disability.

OBJECTIVES: Research and surveillance activities sometimes require that proxy respondents provide key exposure or outcome information, especially for studies of people with disability (PWD). In this study, we compared the health-related quality of life (HRQoL) responses of index PWD to proxies. METHODS: Subjects were selected from nursing home, other assisted living residences, and from several clinic samples of PWD. Each index identified one or more proxy respondents. Computer-assisted interviews used a random order of measures. Proxy reliability was measured by intraclass correlation (ICC) and kappa statistics. HRQoL measures tested included the surveillance questions of the Behavioral Risk Factor Surveillance System (BRFSS), basic and instrumental activities of daily living (ADLs and IADLs), medical outcomes study short-form 36 and 12 (SF-36 and SF-12). RESULTS: A total of 131 index-proxy sets were completed. In general, agreement and reliability of proxy responses to the PWD tended to be best for relatives, with friends lower, and health care proxies lowest. For example, the ICC for the physical functioning scale of the SF-36 was 0.68 for relatives, 0.51 for friends, and 0.40 for healthcare proxies. There was a tendency for proxies to overestimate impairment and underestimate HRQoL. This pattern was reversed for measures of pain, which proxies consistently underestimated. The pattern among instruments, proxy types, and HRQoL domains was complex, and individual measures vary from these general results. CONCLUSIONS: We suggest caution when using proxy respondents for HRQoL, especially those measuring more subjective domains.

Activities of Daily Living↗
PubMed1994

Completeness and accuracy of interview data from proxy respondents: demographic, medical, and life-style factors.

To evaluate the quality of exposure data provided by proxy respondents, we used a dual interview protocol in a case-control study of subarachnoid hemorrhage. All control subjects and their proxy respondents were interviewed (N = 283 control-proxy pairs), as were the cases who were able to provide their own information and their proxy respondents (N = 68 case-proxy pairs). The reliability of proxy-derived data was excellent for demographic and body habitus measures (kappa or intraclass correlation range = 0.86-0.99), and all aspects of cigarette smoking history (range = 0.79-0.93). Proxy reliability was somewhat lower for questions regarding medications and hormone preparations (range = 0.55-0.88), alcohol consumption (range = 0.52-0.82), and recreational physical activity (range = 0.55-0.67). Proxy reliability varied according to the relationship of the proxy to the index subject. Relative to the index subjects, proxy respondents tended to underreport the presence or level of exposure. For most exposures, odds ratios computed with proxy-derived data were similar in magnitude to odds ratios obtained with index subject data; important bias due to differential nonresponse or differential misclassification was suggested only for questions regarding hormone replacement therapy. Epidemiologic studies that rely on proxy respondents may require more subjects to offset the effect of nondifferential nonresponse and misclassification on the precision of effect estimates.

Adolescent↗
PubMed1997

Proxies' decisions about clinical research participation for their charges.

OBJECTIVE: To examine the process by which proxies decide about their charges' participation in clinical research. DESIGN: Using eight hypothetical research studies encompassing a variety of risks and benefits, we interviewed 315 competent persons > or = 65 years old (charges) and, separately, the individuals who would be designated as their proxies if the charges were to become incompetent. The proxies were asked what they thought their charges would decide and what decisions they would make for their charges and for their own participation. SETTINGS: A medical house-call program, two apartment complexes, and three nursing homes. PARTICIPANTS: Charges > or = 65 years old and their proxies. MAIN OUTCOME MEASURE: Comparison of decisions made by charges and by proxies for their charges. RESULTS: The agreement between the proxies' and charges' decisions was not significantly different from random agreement (range of kappa statistics, 0.05-0.15). Rather, proxies' decisions for their charges were significantly related to the proxies' decisions for themselves (kappas, 0.52-0.86). When the paired proxies' and charges' decisions differed, the proxies were protective, more frequently refusing their charges' participation in the perceived riskier research studies. CONCLUSIONS: Proxies did not know what their charges would decide. Their choices for the charges related more to the proxies' decisions about their own participation (which they knew) than to the decisions of their charges (which they didn't know). This is similar to the process of a reasonable person making the decision, a characteristic of decisions made in the best interests of the patient.

Adult↗
PubMed1997

Are proxy assessments of health status after stroke with the EuroQol questionnaire feasible, accurate, and unbiased?

BACKGROUND AND PURPOSE: It is often difficult to determine the health-related quality of life (HRQoL) of stroke patients because physical and cognitive problems limit their ability to complete complex questionnaires. A proxy, such as a family member or caregiver, may be able to give an estimate of the patients' health status. We therefore examined the agreement between the HRQoL as assessed by a series of patients and that assessed by their proxies. METHODS: We studied the validity of the EuroQol in a series of 152 patients from our prospective registry of patients with first (or recurrent) stroke. We asked patients to ensure that a friend or relative (a proxy) who knew them well was available at the time of the interview. We asked each proxy to complete a EuroQol questionnaire independently on behalf of the patient. RESULTS: Proxies completed forms for 130 patients (86%). Agreement between responses from the patients and those from their proxies was better for patients who were able to self-complete the EuroQol than for patients who required the EuroQol to be administered by interview. For both groups, agreement was best for the self-care domain and worst for the domain that assessed psychological outcome. For the more severely affected patients, agreement was only fair for the pain and social functioning domains and no better than chance alone for the psychological functioning domain (kappa = 0.05, 95% confidence interval, 0 to 0.43). Patients tended to rate their own health status as better than their proxies did (P < .05). CONCLUSIONS: We found moderate agreement between responses from patients and those from their proxies for the more directly observable domains of the EuroQol. Proxy agreement was less good for the more subjective domains. In health surveys, allowing responses by a proxy increases response rate. However, the disadvantages inherent in the use of proxy responses must be considered carefully. In general, some domains of HRQoL information obtained from a proxy may be sufficiently valid and unbiased to be useable in most types of trials and surveys.

Caregivers↗
PubMed2004

Quality of life in patients with schizophrenia--comparison of self-report and proxy assessments.

BACKGROUND: While Quality Of Life (QOL) in subjects suffering from schizophrenia has been studied using a variety of generic or specific instruments, only very few studies have analyzed the agreement between patients and proxy ratings on patients' QOL. METHODS: We administered the World Health Organization Quality of Life assessment instrument (WHOQOL-100) to 292 patients and the Quality of Life for Proxies (QOL-P) to their proxies, respectively; the QOL-P is a 30-item instrument derived from the WHOQOL-100 and adapted for administration to a key informant. RESULTS: Agreement between patients and proxies on the four main QOL areas was highest for the physical area (intraclass correlation coefficient, ICC = 0.41) and lowest for the psychological area (ICC = 0.29). In line with the results of other studies comparing patients' and proxies' ratings, proxies generally underestimated patients' physical and psychological QOL. Moreover, the agreement between patients' and proxies' ratings was consistently higher across all QOL areas when the proxy was a relative compared to a non-relative proxy. CONCLUSIONS: The agreement between patients and proxies in QOL assessment is modest, but it is relatively higher when observable aspects of QOL are rated and when the proxy who makes the evaluation is a family member who has closer contacts with the patient. In order to obtain a comprehensive picture of patients' QOL, it would be advisable to compare patients' ratings with the assessments made by close informants.

Adolescent↗
PubMed2005

Contracts, covenants and advance care planning: an empirical study of the moral obligations of patient and proxy.

Previously we had speculated that the patient-proxy relationship existed on a contractual to covenantal continuum. In order to assess this hypothesis, and to better understand the moral obligations of the patient-proxy relationship, we surveyed 50 patient-proxy pairs as well as 52 individuals who had acted as proxies for someone who had died. Using structured vignettes representative of three distinct disease trajectories (cancer, acute stroke, and congestive heart failure), we assessed whether respondents believed that proxies should follow explicit instructions regarding life-sustaining therapy and act contractually or whether more discretionary or covenantal judgments were ethically permissible. Additional variables included the valence of initial patient instructions--for example, "to do nothing" or "to do everything"--as well as the quality of information available to the proxy. Responses were graded on a contractual to covenantal continuum using a modified Likert scale employing a prospectively scored survey instrument. Our data indicate that the patient-proxy relationship exists on a contractual to covenantal continuum and that variables such as disease trajectory, the clarity of prognosis, instructional valence, and the quality of patient instructions result in statistically significant differences in response. The use of interpretative or covenantal judgment was desired by patients and proxies when the prognosis was grim, even if initial instructions were to pursue more aggressive care. Nonetheless, there was a valence effect: patients and proxies intended that negative instructions to be left alone be heeded. These data suggest that the delegation of patient self-determination is morally complex. Advance care planning should take into account both the exercise of autonomy and the interpretative burdens assumed by the proxy. Patients and proxies think inductively and contextually. Neither group viewed deviation from patient instructions as a violation of the principal's autonomy. Instead of adhering to narrow notions of patient self-determination, respondents made nuanced and contextually informed moral judgments. These findings have implications for patient education as well as the legal norms that guide advance care planning.

Advance Care Planning↗
PubMed2004

Comparison of trauma center patient self-reports and proxy reports on the Alcohol Use Identification Test (AUDIT).

BACKGROUND: There has been increased attention on identifying alcohol problems among individuals admitted to trauma centers. Reports about patients' drinking made by significant others represent one potential method to address both concerns about the validity of patients' self-reports and the need to have a proxy measure for trauma patients who are unable to provide information about their drinking behavior. The present study evaluated the level of agreement between trauma patients' self-report and proxy report on the Alcohol Use Disorders Identification Test (AUDIT). METHODS: The study consisted of patients admitted to a Level I trauma center who screened positive for potential alcohol problems, who completed the AUDIT and National Institute of Mental Health Diagnostic Interview Schedule (Form III-R), and who had a collateral who provided proxy information about the patient. Proxy informants completed the AUDIT on the basis of their knowledge and perception of patients' drinking behavior, as well as a checklist of alcohol-related problems experienced by the patients in the 30 days before admission. RESULTS: Patient- and proxy-completed AUDIT total and subscale scores were highly correlated and did not differ from one another except for the dependence subscale, with proxies indicating a higher number of symptoms than did patients. A relatively high percentage of agreement (77.5%) was found overall in the classification of patients as having or not having problem drinking on the basis of self-report and proxy AUDITs; 56.4% of both sources indicated a drinking problem and 21.1% of both agreed that there was not a problem. Patients classified as having problem drinking on self-report AUDITs were rated by proxies as having significantly higher levels of hazardous drinking, alcohol-related problems, and dependence symptoms than patients whose AUDIT classified their drinking as nonproblematic. CONCLUSION: The relative comparability of proxy- and patient-completed AUDIT scores and classifications suggests that patient and proxy reports corroborate and, in cases of trauma patients' inability to provide self-reports, may serve as proxies for patients' reports of drinking.

Adult↗
PubMed1997

Assessing quality of life after stroke. The value and limitations of proxy ratings.

BACKGROUND AND PURPOSE: Because many stroke survivors have cognitive and communication disorders, self-reported information on a patient's quality of life (QL) cannot always be obtained. Proxy ratings may be used to prevent exclusion of this highly relevant subgroup of patients from QL studies. The purpose of this study was to evaluate both the value and possible limitations of such proxy ratings. METHODS: The patient sample was composed of 437 patients who had suffered a stroke 6 months earlier. QL was assessed by means of the Sickness Impact Profile (SIP). For 108 patients who were not communicative because of cognitive or linguistic deficits, proxy ratings on the SIP were provided by the patients' significant others. For 228 of the 329 communicative patients, both self-reported and proxy SIP ratings were obtained. RESULTS: When mean SIP scores for patients with both self-reported and proxy-derived data available were compared, the proxy mean scores were generally in close agreement with those of the patients. However, systematic differences were noted for several SIP scales, with proxies rating patients as having more QL impairments than the patients themselves. Intraclass correlations were moderate to high for most SIP subscales (average intraclass correlation coefficient [ICC] = .63), the physical (ICC = .85) and psychosocial dimensions (ICC = .61), and the total SIP score (ICC = .77). The proxy SIP scores were sensitive to differences in patients' functional health, which supports the validity of these ratings. For all patients combined, more QL impairments were found for patients with supratentorial cortical or subcortical infarctions and hemorrhages than for patients with lacunar infarctions and infratentorial strokes. Although proxy respondents were more frequently needed for patients with the first two types of stroke, we found no evidence of biased results as a consequence of an unbalanced use of proxy respondents across the different types of stroke. CONCLUSIONS: These results suggest that the benefits of using proxy ratings for noncommunicative patients outweigh their limitations. The findings stress the need for inclusion of this important subgroup of patients in QL studies. Their significant others are able to provide useful information on these patients' QL.

Adolescent↗
PubMed1987

The use of proxy responses for aged patients in long-term care settings.

To evaluate the utility of proxy responses for aged residing in a long-term care institution, 106 non-severely cognitively impaired institutionalized patients and their designated proxies were interviewed using an identical interview schedule (53 pairs of patient-proxy interviews). Questions on selected diseases, symptoms and demographic characteristics were included and agreement between respondents and proxies was evaluated. Proxies attempted to provide information on most questions. For many medical diseases and demographic characteristics, proxies provided information which agreed with that provided by patients. However, proxies had more difficulty providing comparable answers about symptoms. It is concluded that a proxy's knowledge of a patient varies by topic. While proxy reports of specific diseases are consistent with the patient's responses, proxy reports of subjective items such as symptoms are not. Recommendations for future research in this area and the importance of these conclusions for other researchers relying on proxy reports are discussed.

Aged↗
PubMed2000

Substituting proxy ratings for patient ratings in cancer clinical trials: an analysis based on a Southwest Oncology Group trial in patients with brain metastases.

In studies of the effect of cancer treatment in the advanced disease setting, researchers have attempted to avoid missing data for quality of life (QOL) assessments by either substituting proxy for patient assessments from the outset or by interspersing proxy measures when patients are unable to respond. Although poor agreement between patient and proxy assessments has been amply demonstrated in the literature, interest in using proxy measures persists. Completion of the Spitzer QL-Index by a small sample of patients with brain metastases and family member proxies provided data for evaluating the ability to substitute proxy for patient QOL assessments. These data cannot address treatment efficacy due to the modest sample size. Rather, the analyses serve to alert researchers to the important distinction (in a clinical trial setting) between agreement and the use of the proxy as a surrogate. We present several methods for evaluating the accuracy of proxy measures and for identifying other sources of error and bias that may vary with time or with treatment arm. Lin's concordance correlation coefficient suggests that proxies are generally a poor substitute for capturing a patient's perspective of his/her QOL. A longitudinal analysis suggests that the use of proxy rather than patient responses could lead to different conclusions concerning radiation therapy's effect on QOL.

Adult↗
PubMed2001

Agreement between patients' and proxies' reports of quality of life in Alzheimer's disease.

Agreement between self reports and proxy reports of health-related quality of life (H RQoL) was examined in a sample of 76 patients with mild to moderate Alzheimer's disease and their proxies. Patients and proxies completed an '17-item Duke health profile'. The items were rephrased for the proxy. The proportion of exact agreement between patients and proxies on the 17 items ranged from 26.3 to 52.6%. Results reveal poor to moderate agreement (intraclass correlation coefficients (ICCs) from 0.00 to 0.61 for 10 subscales) between patients' and proxies' reports. Agreement was higher for measures of function that are directly observable (physical health, disability) and relatively poor for more subjective measures. Proxy reliability varied according to the relationship of the proxy to the index subject. Spouses and nurses agreed more closely with index subjects than did children or nurses' aides. Agreement decreased with increasing severity of dementia. Statistically significant differences in mean scores were noted for several dimensions, with proxies tending to rate the patients as having a lower quality of life than the patients themselves. This study indicates the importance of considering the information source of a patient's HRQoL. However, assessments by proxies should be used with caution.

Aged↗
PubMed2001

How proxies make decisions about research for patients with Alzheimer's disease.

We examined the proxy decision-making and informed consent processes for clinical research involving 49 patient-subjects with dementia in an outpatient setting by performing serial in-depth, structured, open-ended telephone interviews. Interviews were tape recorded and transcribed. Transcripts were then coded and analyzed. Although in all cases proxy consent was obtained for research from a legally authorized representative, proxies reported considerable ambiguity regarding who made the decision to participate in research, or to what degree the decision was that of the proxy or of the patient. Reasons proxies gave for participating in research included: hope of direct or indirect benefits to the patient, caregiver, or patient's descendents; desperation; trust in the investigator; belief in the goodness of research; and altruism. These reasons varied according to the type of research. For instance, in drug trials hope of direct benefit prevailed; in studies not evaluating a potential therapy more altruistic concerns predominated. Being a proxy decision maker for research can be burdensome. The degree of burden related to making a decision to participate in research seems influenced by a number of intersecting factors, most importantly, the risk and nature of the study, the extent to which patients were able to participate in the decision, and the duration and severity of dementia. Proxy decision-making concerning participation in research for patients with dementia can be a difficult task. The process might be improved by emphasizing that proxy consent is being sought because the nature of the patient's underlying medical condition can preclude the ability to make meaningful decisions. In addition, clinical researchers should recognize that giving proxy consent might place additional burdens on caregivers and discuss this explicitly when proxy consent is solicited.

Aged↗
PubMed2005

Proxy sources for information on nursing home residents' quality of life.

OBJECTIVES: This study explores how well staff and family proxies' reports on selected quality-of-life (QOL) domains (comfort, dignity, functional competence, privacy, meaningful activity, food enjoyment, relationships, security, and autonomy) correspond to residents' own reports. METHODS: We compared QOL domain scores for nursing home residents and 1,326 staff proxies and 989 family proxies at the individual and facility level using means, Pearson correlation statistics, and intraclass correlations. Regression models adjusted for residents' age, gender, length of stay, ability to perform activities of daily living, and cognition. RESULTS: For each domain in more than half the cases, proxy means were within 1 SD of the resident means. Resident and family proxy individual reports for selected domains were correlated at 0.14 to 0.46 (all p <.000). Resident and staff proxy individual reports were correlated at 0.13 to 0.37 (all p <.000). Correlation of mean levels by facility for staff proxies was 0.26 to 0.64 (generally p <.05) and for family proxies 0.13 to 0.61 (p <.01 except for one domain). DISCUSSION: Although staff and family proxy domain scores are significantly correlated with resident scores, the level of correlation suggests they cannot simply be substituted for resident reports of QOL. Determining how proxy reports can be used for residents who cannot be interviewed at all remains an unresolved challenge.

Activities of Daily Living↗
PubMed2002

Proxy reporting of quality of life using the EQ-5D.

BACKGROUND: The economic evaluation of health interventions for older people is complicated by the difficulty in obtaining self-reports of quality of life from persons with cognitive impairments, physical impairments, or both. OBJECTIVES: Using the EQ-5D (EuroQoL) measures, to assess: (1) agreement between subjects and proxies on subject's quality of life ratings at different points in time; (2) agreement between subjects and proxies on change of subject's quality of life ratings over time; and (3) subject and proxy characteristics related to agreement. RESEARCH DESIGN: Prospective study of subjects visiting hospital emergency departments (ED). Data were collected at enrollment in the ED and at follow-up, 1 and 4 months after the ED visit. SUBJECTS: The study comprised 231 pairs of cognitively intact patients aged 65 years or older and their primary caregivers. MEASURES: Quality of life was measured using both components of the EQ-5D scale, the index score and the Visual Analogue Scale (VAS). Demographic characteristics and health status (physical and mental) were measured for both subjects and proxies. Subjects and proxies were interviewed either in English or French. RESULTS: There was low to moderate agreement between subjects and proxies at different points in time (intraclass correlation coefficient [ICC] = 0.22 to 0.59), and between subject and proxy change scores over time (ICC = 0-0.50), on both the index score and the VAS. Better agreement between subjects and proxies was found at the 4 months follow-up, when the subject was less depressed, and when the proxy's native language was English. CONCLUSIONS: Proxy EQ-5D responses, either for a specific point in time or for assessing change over time, may not be valid measures of self-reported quality of life among older medically-ill patients.

Aged↗
PubMed1999

Influence of proxy respondents in children's health interview surveys.

STUDY OBJECTIVES: To study the influence of the proxy respondent on health interview surveys in children. DESIGN: Cross sectional study. SETTING: Children under the age of 15 years drawn from the general population of Catalonia, Spain. PARTICIPANTS: The Catalan Health Interview Survey consisted of a multistage probability sample representative to the population of Catalonia. The sample size was 2433 children younger than 15 years of age. The interviews were answered by proxy respondents (the mother, father, or other carer), with the questionnaire adapted for the proxy respondent. Logistic regression models were used to analyse the relation between the proxy respondent's characteristics and health status and health care utilisation, controlling for the effect of sociodemographic factors. MAIN RESULTS: Proxy respondent's characteristics influenced the reports of chronic conditions and accidents within the last year. Proxy respondents over 55 years (OR = 0.47; 95% CI = 0.26, 0.82), men (OR = 0.69; 95% CI = 0.53, 0.89), the father (OR = 0.66; 95% CI = 0.50, 0.89), and the grandparents (OR = 0.49; 95% CI = 0.26, 0.89), reported a lower rate of chronic conditions. Age of the proxy 55 years or greater (OR = 0.41; 95% CI = 0.20, 0.82), men (OR = 0.70; 95% CI = 0.52, 0.94), fathers (OR = 0.68; 95% CI = 0.49, 0.92), and grandparents (OR = 0.40; 95% CI = 0.18, 0.85) showed a lower probability to report accidents. No variables related to the proxy were associated with physician visits or hospitalisation in the previous year. CONCLUSIONS: Selected characteristics of the proxy respondent can influence responses to health surveys involving children. A minimum set of basic data should be collected from the proxy respondent to evaluate different patterns of response.

Adolescent↗
PubMed1992

Misclassification of exposure in a case-control study: the effects of different types of exposure and different proxy respondents in a study of pancreatic cancer.

This investigation addressed three questions about misclassification in a case-control study of risk factors for pancreatic cancer in which all exposure data were obtained from proxy respondents. These questions were: (1) To what degree was misclassification dependent on the type of exposure? (2) To what degree did misclassification vary by the type of proxy? (3) What was the magnitude of the effect of proxy misclassification on odds ratios measured across several levels of exposure? To answer these questions, we interviewed 163 control (index) subjects and next-of-kin (proxy) respondent pairs. Each of the controls and their respective proxies reported the control's use of coffee, cigarettes, and alcohol and weekly exposure to beef, milk, bacon, fruits, and vegetables. Nonspouse proxies misclassified exposures more than spouse proxies with the exception of cigarettes. Cigarette use was the most accurately reported exposure, followed by alcohol, coffee, and foods. For nondifferential misclassification between cases and controls, the slope of a dose-response curve was decreased from 6.6% to 100% depending on the exposure and the type of proxy respondent. Investigators conducting studies using proxy respondents need to recognize that misclassification is a function of multiple factors, including both the type of exposures under study and the type of proxies available.

Adult↗
PubMed2000

Agreement between older subjects and proxy informants on history of surgery and childbirth.

OBJECTIVES: To assess the agreement between proxy informants' reports of history of surgery and childbirth and older index subjects' own recall. DESIGN: Interrater reliability study. SETTING: An outpatient family medicine clinic and a provincial electoral district in Montreal, Canada. PARTICIPANTS: Eighty-two subjects aged 65 years and older without cognitive impairment, identified from clinic and community settings, and each index subject's proxy respondent. MEASUREMENTS: Identical questionnaires were administered to index subjects and proxies. RESULTS: Proxies failed to report 39% of non-childbirth surgeries reported by index subjects, but failed to report only 10% of childbirths. Female proxies were significantly less likely than male proxies to underreport non-childbirth surgeries after controlling for age of index subject and interval since surgery. Longer interval since surgery was significantly associated with greater underreporting, whereas age of the index subject and relationship between proxy and index subject were not. Agreement between proxies and index subjects on date of surgery was much higher for childbirths than for non-childbirth surgeries. CONCLUSIONS: Our findings suggest that proxy respondents can provide reliable information on older women's history of childbirth but that use of proxy respondents for history of non-childbirth surgeries may result in substantial underreporting.

Age Factors↗
PubMed1997

Social comparison and task prediction: ability similarity and the use of a proxy.

It is argued that an important aspect of the self-appraisal of ability involves a person's prediction of his or her own performance level on untried tasks through acquisition of knowledge about how other people have fared at the task. These others are treated as substitutes for a person's own participation in the task--as proxies. It is further argued that social comparison plays a significant role in both the selection of proxies and the impact of proxy information on task prediction. The first experiment, following earlier research on comparison preference in the context of performance prediction, showed that participants interested in performance prediction chose a proxy who had performed at about the same level as they had on a reference task, while those interested in improving their performances chose to see the performances of someone who had done far better than they on the reference task. The second study indicated that participants made more confident predictions for themselves from a similar proxy's task outcome than from that of a proxy whose ability was unknown to them. Participants predicted they would do worse than a more able proxy and better than a less able proxy, but were less confident in their predictions than were those with a similar proxy. Ratings of usefulness of the proxy followed the patterns of confidence ratings closely.

Aptitude↗