Results

Distractor analysis

'breaks' are not unique

Instructions

Enter the correct answer separated by commas, but there must be no spaces between commas.
The distractor analysis uses a fixed 3-group structure(33%-34%-33%) to ensure stable and reliable results.
By a rule of thumb, all items with a discrimination lower than 0.2 (threshold in the plot), should be checked for content.
Feature requests and bug reports can be made on my GitHub.

Counts of respondents

Item Q1
	lower	middle	upper

Item Q2
	lower	middle	upper

Item Q3
	lower	middle	upper

Item Q4
	lower	middle	upper

Item Q5
	lower	middle	upper

Item Q6
	lower	middle	upper

Item Q7
	lower	middle	upper

Item Q8
	lower	middle	upper

Item Q9
	lower	middle	upper

Item Q10
	lower	middle	upper

Item Q11
	lower	middle	upper

Item Q12
	lower	middle	upper

Item Q13
	lower	middle	upper

Item Q14
	lower	middle	upper

Item Q15
	lower	middle	upper

[3]

Descriptives

Descriptives
	TOTAL
N	79
Missing	0
Mean	13.1
Median	14.0
Mode	15.0
Standard deviation	2.31
Minimum	2.00
Maximum	15.0

Plots

TOTAL

Dichotomous Model

Instructions

Each variable must be coded as 0 or 1 with the type of numeric-continuous in jamovi.
Use variable names with exactly one trailing number (e.g., i1, item2, age1); names without digits or with multiple numbers may not plot.
The rationale of snowIRT module is described in the documentation.
Feature requests and bug reports can be made on my GitHub.

Item Statistics
	Proportion	Measure	Infit	Outfit
Q1_conv	0.962	-4.02	0.634	0.138
Q2_conv	0.949	-3.67	0.652	0.198
Q3_conv	0.911	-2.95	0.820	0.872
Q4_conv	0.911	-2.95	0.976	0.836
Q5_conv	0.772	-1.57	1.078	1.147
Q6_conv	0.937	-3.39	1.037	1.185
Q7_conv	0.848	-2.20	0.949	0.995
Q8_conv	0.835	-2.08	1.098	1.090
Q9_conv	0.962	-4.02	0.788	0.381
Q10_conv	0.924	-3.16	0.909	1.014
Q11_conv	0.823	-1.97	1.195	1.171
Q12_conv	0.810	-1.86	0.931	0.724
Q13_conv	0.696	-1.07	0.973	0.975
Q14_conv	0.962	-4.02	0.766	0.285
Q15_conv	0.810	-1.86	1.499	1.963
Note. Infit= Information-weighted mean square statistic; Outfit= Outlier-sensitive means square statistic.
[5]

Model Fit

Model Fit
	Person Reliability
scale	0.251
[5]

Wright Map

[6]

Item Infit Plot

Item Outfit Plot

Reliability Analysis

Scale Reliability Statistics
	Cronbach's α
scale	0.722
Note. item 'Q15_conv' correlates negatively with the total scale and probably should be reversed
[7]

Item Reliability Statistics
	If item dropped
	Cronbach's α
TOTAL	0.756
Q1_conv	0.704
Q2_conv	0.701
Q3_conv	0.702
Q4_conv	0.708
Q5_conv	0.705
Q6_conv	0.714
Q7_conv	0.701
Q8_conv	0.709
Q9_conv	0.710
Q10_conv	0.707
Q11_conv	0.714
Q12_conv	0.697
Q13_conv	0.696
Q14_conv	0.709
Q15_conv	0.733

References

[1] The jamovi project (2025). jamovi. (Version 2.7) [Computer Software]. Retrieved from https://www.jamovi.org.

[2] R Core Team (2025). R: A Language and environment for statistical computing. (Version 4.5) [Computer software]. Retrieved from https://cran.r-project.org. (R packages retrieved from CRAN snapshot 2025-05-25).

[3] Willse, J. (2018). CTT: Classical Test Theory Functions. (Version 2.3.3) [R package]. URL https://CRAN.R-project.org/package=CTT.

[4] Seol, H. (2026). snowIRT: Item Response Theory for jamovi. (Version 5.1.8) [jamovi module]. URL https://github.com/hyunsooseol/snowIRT.

[5] Robitzsch,A., Kiefer, T., & Wu, M. (2020). TAM: Test Analysis Modules. (Version 4.1.4) [R package]. URL https://CRAN.R-project.org/package=TAM.

[6] Martinkova, P., & Drabinova, A. (2018). ShinyItemAnalysis: for teaching psychometrics and to enforce routine analysis of educational tests. (Version 1.4.2) [R package]. URL https://CRAN.R-project.org/package=ShinyItemAnalysis.

[7] Revelle, W. (2025). psych: Procedures for Psychological, Psychometric, and Personality Research. [R package]. Retrieved from https://cran.r-project.org/package=psych.