Ability of a measure increases as the number of items increase (Carmines and Zeller, 1979). Thus, the five-item PRDS might be more reliable–or at 
least internally consistent– than the single-item SES ladder simply because it has more items. Further, the PRDS and SES ladder measures differ in the 
total number of scale points used within the response scales (6 vs. 10, respectively), which can also affect the accuracy of measures (Krosnick and Presser, 2010). We addressed this issue across Studies 4?. In Study 4, along with the SES ladder measure of SSS we used in Studies 1?, we used a single-item from the PRDS and asked participants to rate their agreement on a 10-point scale (which matches the 10-point scale of the SES ladder measure). Given its theoretical importance in the links between PRD and health and SSS and health, we zeroed in on perceived stress as our single criterion variable in Study 4.Perceived stressParticipants completed the four-item Perceived Stress Scale (Cohen and Williamson, 1988): “In the last month, how often have you felt that you were unable to control the important things in your life?”; “In the last month, how often have you felt confident about your ability to handle your personal problems?”; “In the last month, how often have you felt that things were going your way?”; and “In the last month, how often have you felt difficulties were piling up so high that you could not overcome them?.” Items were rated on a 5-point scale (1 = never, 5 = very often), and higher scores indicate greater perceived stress.Objective socioeconomic statusWe measured annual household income and educational attainment as in Studies 1 and 2 (see Table 1).Methods ParticipantsParticipants from the USA were recruited as in Studies 1 and 2 (N = 400). Sample characteristics are shown in Table 1.Results and DiscussionShown in Table 6, both the single-item PRDS and SSS correlated significantly with perceived stress. Shown in Table 3, multiple regression analyses regressing perceived stress onto PRDS, SSS, income, and education showed that although both PRDS and SSS accounted for significant incremental variance in stress, PRDS accounted for more unique variance in, and was the generally dominant predictor of, perceived stress (reproducibility value of 90 ).Procedure and MeasuresParticipants first completed the visual analog SSS measure and a single-item PRDS in a random order. They then completed a perceived stress scale and provided their education and annual household income.Frontiers in Psychology | www.frontiersin.orgSeptember 2015 | Volume 6 | c-Met inhibitor 2 biological activity GS-4059 site ArticleCallan et al.Relative deprivationTABLE 6 | Descriptive statistics and intercorrelations for measures in Study 4. Measures 1. SSS 2. Single-item PRDS 3. Stress 4. Income 5. Education M (SD) 5.01 (1.81) 1 ??0.42** -0.34** -0.28**Procedure and MeasuresParticipants completed the following measures in order:Comparisons with people in the USA and similar othersUsing a single-item measure of SSS from previous research (which has been shown to correlate with self-rated health; Wolff et al., 2010), we asked participants to rate their relative standing compared with people in the USA:5.09 (2.16) -0.57** 2.55 (0.83) -0.39** 4.01 (1.85) 2.76 (0.71)0.60** 0.40**?-0.31** -0.19**?0.35**?SSS, Subjective Socioeconomic Status; PRDS, Personal Relative Deprivation Scale. Higher values indicate more of each construct. **p <0.01.StudyIn Study 4, perceived stress was better predicted by a singleitem from the PRD.Ability of a measure increases as the number of items increase (Carmines and Zeller, 1979). Thus, the five-item PRDS might be more reliable--or at least internally consistent-- than the single-item SES ladder simply because it has more items. Further, the PRDS and SES ladder measures differ in the total number of scale points used within the response scales (6 vs. 10, respectively), which can also affect the accuracy of measures (Krosnick and Presser, 2010). We addressed this issue across Studies 4?. In Study 4, along with the SES ladder measure of SSS we used in Studies 1?, we used a single-item from the PRDS and asked participants to rate their agreement on a 10-point scale (which matches the 10-point scale of the SES ladder measure). Given its theoretical importance in the links between PRD and health and SSS and health, we zeroed in on perceived stress as our single criterion variable in Study 4.Perceived stressParticipants completed the four-item Perceived Stress Scale (Cohen and Williamson, 1988): "In the last month, how often have you felt that you were unable to control the important things in your life?"; "In the last month, how often have you felt confident about your ability to handle your personal problems?"; "In the last month, how often have you felt that things were going your way?"; and "In the last month, how often have you felt difficulties were piling up so high that you could not overcome them?." Items were rated on a 5-point scale (1 = never, 5 = very often), and higher scores indicate greater perceived stress.Objective socioeconomic statusWe measured annual household income and educational attainment as in Studies 1 and 2 (see Table 1).Methods ParticipantsParticipants from the USA were recruited as in Studies 1 and 2 (N = 400). Sample characteristics are shown in Table 1.Results and DiscussionShown in Table 6, both the single-item PRDS and SSS correlated significantly with perceived stress. Shown in Table 3, multiple regression analyses regressing perceived stress onto PRDS, SSS, income, and education showed that although both PRDS and SSS accounted for significant incremental variance in stress, PRDS accounted for more unique variance in, and was the generally dominant predictor of, perceived stress (reproducibility value of 90 ).Procedure and MeasuresParticipants first completed the visual analog SSS measure and a single-item PRDS in a random order. They then completed a perceived stress scale and provided their education and annual household income.Frontiers in Psychology | www.frontiersin.orgSeptember 2015 | Volume 6 | ArticleCallan et al.Relative deprivationTABLE 6 | Descriptive statistics and intercorrelations for measures in Study 4. Measures 1. SSS 2. Single-item PRDS 3. Stress 4. Income 5. Education M (SD) 5.01 (1.81) 1 ??0.42** -0.34** -0.28**Procedure and MeasuresParticipants completed the following measures in order:Comparisons with people in the USA and similar othersUsing a single-item measure of SSS from previous research (which has been shown to correlate with self-rated health; Wolff et al., 2010), we asked participants to rate their relative standing compared with people in the USA:5.09 (2.16) -0.57** 2.55 (0.83) -0.39** 4.01 (1.85) 2.76 (0.71)0.60** 0.40**?-0.31** -0.19**?0.35**?SSS, Subjective Socioeconomic Status; PRDS, Personal Relative Deprivation Scale. Higher values indicate more of each construct. **p <0.01.StudyIn Study 4, perceived stress was better predicted by a singleitem from the PRD.