Table with detailed item statistics for one scale — nice_item

Returns a data.frame with detailed item analyses for the provided scale.

nice_item_analysis(
  data,
  scales,
  labels = NULL,
  round = 2,
  ci = FALSE,
  conf_level = 0.95,
  check_key = TRUE,
  keys = NULL,
  keys_from_weights = FALSE,
  RMSEA = FALSE,
  difficulty = FALSE,
  values = NULL,
  fa = TRUE,
  alpha_dropped = TRUE,
  use_col_labels = FALSE,
  ...
)

Arguments

data: A data Frame.
scales: A list with vectors with variable names that define each scale.
labels: Optional labels for the items in the scale.
round: Rounds values to given decimal position.
ci: If TRUE confidence intervals are calculated.
conf_level: Confidence level (e.g. 0.95 for 95 percent).
check_key: Check_key for the psych::alpha function.
keys: Optional key argument for the psych::alpha function.
keys_from_weights: If TRUE, tries to define keys from the weights dictionary attribute. These are only available when you defined them with the scaledic package.
RMSEA: If TRUE RMSEA is calculated.
difficulty: If TRUE, the difficulty of the item is calculated.
values: Sets maximum and minimum valid values necessary to calculate item difficulty.
fa: If TRUE, a one factor exploratory factor analyses is calculated and loadings are reported.
use_col_labels: If TRUE, variable names are taken from a label attribute.
...: Further arguments passed to the nice_table() function.

Value

A data frame with concise scale indices.

Details

This function is a wrapper around the psych::alpha() function from the psych package. It computes item-total correlations, scale mean and standard deviation, Cronbach's alpha (with optional confidence intervals), standardized alpha, item difficulty, and factor loadings from a one-factor exploratory factor analysis.

Author

Juergen Wilbert

Examples

nice_item_analysis(
  data_emo, 
  scale = data_emo_scales, 
  difficulty = TRUE, 
  values = c(1,5)
)


  Table
Item analysis
    
Labels
      M
      SD
      r_it
      ΔAlpha
      Loadings
      Difficulty
    
Grundeinstellung
n = 146; Alpha = .68; Std. alpha = .68; Homogeneity = .26
    
F2
2.54
1.15
0.60
-0.12
0.83
0.39
F3
1.86
1.11
0.29
0.00
0.42
0.21
F26-
2.58
1.08
0.30
-0.01
-0.33
0.39
F27
2.49
1.10
0.41
-0.04
0.57
0.37
F28
2.90
1.10
0.48
-0.07
0.51
0.47
F29
3.23
0.92
0.37
-0.03
0.39
0.56
Resilienz
n = 146; Alpha = .60; Std. alpha = .60; Homogeneity = .23
    
F6
2.40
1.06
0.30
-0.03
0.41
0.35
F10
1.98
1.17
0.37
-0.06
0.49
0.24
F14
2.29
1.06
0.40
-0.08
0.56
0.32
F25-
1.72
1.13
0.34
-0.05
-0.45
0.18
F32-
2.49
1.18
0.36
-0.06
-0.49
0.37
Intuition
n = 145; Alpha = .80; Std. alpha = .81; Homogeneity = .41
    
F1
3.00
0.97
0.60
-0.04
0.70
0.50
F4
2.85
0.96
0.68
-0.06
0.78
0.46
F5
3.08
0.93
0.63
-0.05
0.71
0.52
F16
3.20
0.73
0.50
-0.02
0.58
0.55
F20-
2.99
0.99
0.41
0.01
-0.45
0.50
F23
2.79
1.05
0.57
-0.03
0.63
0.45
Selbstwahrnehmung
n = 146; Alpha = .72; Std. alpha = .72; Homogeneity = .39
    
F11
2.47
1.09
0.45
-0.02
0.53
0.37
F17
2.77
0.97
0.63
-0.14
0.83
0.44
F18
2.78
0.95
0.48
-0.05
0.59
0.44
F31-
2.76
0.98
0.47
-0.04
-0.57
0.44
Sensibilität
n = 146; Alpha = .57; Std. alpha = .58; Homogeneity = .21
    
F8
2.58
0.91
0.20
0.01
0.29
0.39
F12
2.66
0.95
0.40
-0.10
0.56
0.42
F21
2.68
0.87
0.45
-0.12
0.65
0.42
F22-
3.27
0.99
0.38
-0.08
-0.50
0.57
F30-
2.59
1.05
0.25
-0.01
-0.34
0.40
Aufmerksamkeit
n = 146; Alpha = .80; Std. alpha = .80; Homogeneity = .41
    
F7
2.00
1.09
0.55
-0.03
0.62
0.25
F9-
1.41
1.01
0.58
-0.03
-0.65
0.10
F13
2.23
1.25
0.52
-0.02
0.59
0.31
F15
2.20
1.20
0.69
-0.06
0.81
0.30
F19
1.71
1.05
0.52
-0.02
0.58
0.18
F24
1.65
1.15
0.51
-0.02
0.57
0.16
 Note. r_it is the item-total correlation. Homogeneity is the average inter-item correlation. Difficulty is mean rescaled to [0,1]. ΔAlpha is the change in raw alpha when the item is dropped. Loadings are based on a one factor exploratory factor analysis.

Labels	M	SD	r_it	ΔAlpha	Loadings	Difficulty
Table Item analysis
Grundeinstellung n = 146; Alpha = .68; Std. alpha = .68; Homogeneity = .26
F2	2.54	1.15	0.60	-0.12	0.83	0.39
F3	1.86	1.11	0.29	0.00	0.42	0.21
F26-	2.58	1.08	0.30	-0.01	-0.33	0.39
F27	2.49	1.10	0.41	-0.04	0.57	0.37
F28	2.90	1.10	0.48	-0.07	0.51	0.47
F29	3.23	0.92	0.37	-0.03	0.39	0.56
Resilienz n = 146; Alpha = .60; Std. alpha = .60; Homogeneity = .23
F6	2.40	1.06	0.30	-0.03	0.41	0.35
F10	1.98	1.17	0.37	-0.06	0.49	0.24
F14	2.29	1.06	0.40	-0.08	0.56	0.32
F25-	1.72	1.13	0.34	-0.05	-0.45	0.18
F32-	2.49	1.18	0.36	-0.06	-0.49	0.37
Intuition n = 145; Alpha = .80; Std. alpha = .81; Homogeneity = .41
F1	3.00	0.97	0.60	-0.04	0.70	0.50
F4	2.85	0.96	0.68	-0.06	0.78	0.46
F5	3.08	0.93	0.63	-0.05	0.71	0.52
F16	3.20	0.73	0.50	-0.02	0.58	0.55
F20-	2.99	0.99	0.41	0.01	-0.45	0.50
F23	2.79	1.05	0.57	-0.03	0.63	0.45
Selbstwahrnehmung n = 146; Alpha = .72; Std. alpha = .72; Homogeneity = .39
F11	2.47	1.09	0.45	-0.02	0.53	0.37
F17	2.77	0.97	0.63	-0.14	0.83	0.44
F18	2.78	0.95	0.48	-0.05	0.59	0.44
F31-	2.76	0.98	0.47	-0.04	-0.57	0.44
Sensibilität n = 146; Alpha = .57; Std. alpha = .58; Homogeneity = .21
F8	2.58	0.91	0.20	0.01	0.29	0.39
F12	2.66	0.95	0.40	-0.10	0.56	0.42
F21	2.68	0.87	0.45	-0.12	0.65	0.42
F22-	3.27	0.99	0.38	-0.08	-0.50	0.57
F30-	2.59	1.05	0.25	-0.01	-0.34	0.40
Aufmerksamkeit n = 146; Alpha = .80; Std. alpha = .80; Homogeneity = .41
F7	2.00	1.09	0.55	-0.03	0.62	0.25
F9-	1.41	1.01	0.58	-0.03	-0.65	0.10
F13	2.23	1.25	0.52	-0.02	0.59	0.31
F15	2.20	1.20	0.69	-0.06	0.81	0.30
F19	1.71	1.05	0.52	-0.02	0.58	0.18
F24	1.65	1.15	0.51	-0.02	0.57	0.16
Note. r_it is the item-total correlation. Homogeneity is the average inter-item correlation. Difficulty is mean rescaled to [0,1]. ΔAlpha is the change in raw alpha when the item is dropped. Loadings are based on a one factor exploratory factor analysis.