Table 3.
Factor loadings, discrimination, threshold, and difficulty parameters for SDE for dichotomous and polytomous scoring.
| Items | Dichotomous scoring | Polytomous scoring | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Factor loading | a1 | a2 | b | Factor loading | a1 | a2 | Difficulty (b) | |||||||||
| 1 | 2 | 1 | 2 | 1 | 2 | 3 | 4 | 5 | 6 | |||||||
| Self-deceptive enhancement | ||||||||||||||||
| 1 | My first impressions of people usually turn out to be right. | .32 | 0.57 | 1.28 | .33 | 0.60 | −7.87 | −6.43 | −4.57 | −1.55 | 1.28 | 4.80 | ||||
| 3 | I do not care to know what other people really think of me. | .63 | 1.39 | 1.78 | ||||||||||||
| 5 | I always know why I like things. | .60 | 1.27 | 0.34 | .60 | 1.27 | −4.17 | −2.61 | −1.65 | −0.71 | 0.34 | 2.00 | ||||
| 7 | Once I’ve made up my mind, other people can seldom change my opinion. | .33 | 0.59 | 1.83 | .22 | 0.38 | −9.53 | −5.30 | −2.34 | 0.15 | 2.73 | 6.85 | ||||
| 9 | I am fully in control of my own fate. | .61 | 1.31 | −1.20 | .47 | 0.91 | −3.17 | −2.26 | −1.29 | 0.28 | 1.50 | 3.13 | ||||
| 11 | I never regret my decisions. | .58 | 1.22 | 2.21 | .36 | 0.66 | −3.34 | −0.98 | 0.65 | 2.30 | 3.50 | 6.26 | ||||
| 13 | The reason I vote is because my vote can make a difference. | .32 | 0.58 | 1.42 | .16 | 0.28 | −6.75 | −4.88 | −3.08 | −0.23 | 2.75 | 7.21 | ||||
| 15 | I am a completely rational person. | .62 | 1.33 | 1.41 | .44 | 0.83 | −2.96 | −1.84 | −0.87 | 0.65 | 1.92 | 3.90 | ||||
| 17 | I am very confident of my judgments | .74 | 1.86 | 0.95 | ||||||||||||
| 19 | It is all right with me if some people happen to dislike me. | .40 | 0.75 | 1.08 | .23 | 0.40 | −7.02 | −4.04 | −2.29 | −0.17 | 1.86 | 5.09 | ||||
| 2 | It would be hard for me to break any of my bad habits. | .51 | 1.01 | 1.35 | .44 | 0.82 | −4.61 | −2.40 | −0.79 | 0.49 | 1.55 | 3.05 | ||||
| 4 | I have not always been honest with myself. | .63 | 1.51 | 0.89 | .59 | 1.25 | −2.82 | −1.62 | −0.50 | 0.34 | 0.92 | 2.30 | ||||
| 6 | When my emotions are aroused, it biases my thinking. | .59 | 1.23 | 1.97 | .48 | 0.94 | −2.74 | −0.95 | 0.29 | 1.56 | 2.34 | 3.75 | ||||
| 8 | I am not a safe driver when I exceed the speed limit. | .35 | 0.63 | 0.22 | .17 | 0.30 | −8.71 | −6.11 | −3.97 | −1.70 | 0.40 | 4.14 | ||||
| 10 | It is hard for me to shut off a disturbing thought. | .59 | 1.24 | 1.62 | .56 | 1.15 | −2.51 | −1.05 | 0.13 | 1.00 | 1.67 | 3.24 | ||||
| 12 | I sometimes lose out […] because I cannot make up my mind soon enough. | .53 | 1.07 | 0.79 | .47 | 0.89 | −4.43 | −2.37 | −1.03 | −0.14 | 0.87 | 2.63 | ||||
| 14 | My parents were not always fair when they punished me. | .43 | 0.80 | −0.27 | .36 | 0.67 | −4.99 | −3.67 | −2.45 | −1.16 | −0.33 | 1.37 | ||||
| 16 | I rarely appreciate criticism. | .31 | 0.56 | 0.78 | .23 | 0.40 | −14.28 | −6.97 | −4.16 | −1.88 | 1.03 | 5.33 | ||||
| 18 | I have sometimes doubted my ability as a lover. | .54 | 1.08 | 0.80 | .48 | 0.92 | −3.85 | −1.98 | −0.83 | 0.18 | 0.89 | 2.19 | ||||
| 20 | I do not always know the reasons why I do the things I do. | .75 | 1.91 | 0.92 | .65 | 1.44 | −2.61 | −1.39 | −0.47 | 0.39 | 1.02 | 2.19 | ||||
a is the discrimination parameter (or slope). For polytomous scoring, given that each item has 7 item categories, there are six thresholds (i.e., difficulty parameter, b) creating these seven categories. The mirt package in R only provides estimates for intercepts which can be transformed into threshold values for each item using the following formula (−d/a), where d is the intercept value for the corresponding response category and a is the slope for the item. The intercept together with confidence intervals can be found in Supplementary material S1. Darker notation indicate greater factor loadings (< .40; .40–.55; ≥ .55) and discrimination parameters (< 0.65; 0.65–1.34; > 1.34). Items 3 and 17 indicated local dependence for polytomous scoring method.