Introduction
Material and methods
Participants and study design
Procedures and measurements
Migraine screen questionnaire
Visual analog scale for attention
Socio-demographic questionnaire
Statistical analysis
Results
Participants’ characteristics and preliminary item analysis
Characteristics | Mean ± SD/frequency |
---|---|
Age (yr) | 21.08 ± 1.93 |
15–19a | 51(14.9) |
20–24 | 267(77.8) |
25–29 | 15(4.4) |
30–34 | – |
35–39 | 1(0.3) |
Unreported | 9(2.6) |
BMI (Kg/m2) | |
Underweight | 44(12.8) |
Normal | 230(67.1) |
Over-weight | 18(5.2) |
Obese | 8(2.3) |
Unreported | 43(12.5) |
Gender | |
Male | 23.9(69.7) |
Female | 85(24.8) |
Unreported | 19(5.5) |
Attendance (percentage) | |
50–60 | 4(1.2) |
61–70 | 2(0.6) |
71–80 | 14(4.1) |
81–90 | 33(9.6) |
91–100 | 186(54.2) |
Unreported | 104(30.3) |
Grade | |
Satisfactory (2–2.49 number grade) | 23(6.7) |
Good (2.5–2.99 number grade) | 57(16.6) |
Very good (3–3.74 number grade) | 96(28.0) |
Excellent (3.75–4 number grade) | 49(14.3) |
Unreported | 118(34.4) |
Migraine (According to MS-Q)b | |
Migraine | 67(19.5) |
No migraine | 276(80.5) |
Items of the MS-Q | Skewness | kurtosis | Item-total Correlationsa | I-ECV | IREAL | Communality (h2)b | Factor loadingb |
---|---|---|---|---|---|---|---|
Do you have frequent or intense headaches? | 0.259 | −1.930 | .75* | 0.913 | 0.247 | 0.707 | 0.798 |
Do your headaches usually last more than 4 h? | 1.158 | −0.660 | .68* | 0.885 | 0.303 | 0.797 | 0.835 |
Do you usually suffer from nausea when you have a headache? | 1.289 | −0.340 | .65* | 0.999 | 0.030 | 0.688 | 0.802 |
Does light or noise bother you when you have a headache? | 0.454 | −1.791 | .76* | 0.816 | 0.428 | 0.914 | 0.848 |
Does headache limit any of your physical or intellectual activities? | −0.012 | −1.997 | .76* | 0.977 | 0.118 | 0.662 | 0.781 |
Factorial validity
Sample adequacy and sample suitability for factor analysis
Measures | Values |
---|---|
Multivariate descriptive | |
Mardia’s skewness | Χ2(df = 35) = 271.190, p = 1.00 |
Mardia’s kurtosis | Χ2 = 0.513, p = 0.3038 |
Quality and effectiveness of factor score estimatesa | |
Factor Determinacy Index (FDI) | 0.953 |
expected a posteriori marginal reliability | 0.909 |
Construct replicabilitya | |
H-Latent | 0.909 |
H-Observed | 0.727 |
Sample size adequacy | |
Bartlett’s test of Sphericity | Χ2(df = 10) = 430.3, p < 0.001 |
Determinant | 0.282 |
KMO (95% confidence interval) | 0.804 (0.770–0.845) |
Internal consistency | |
Greatest Lower Bound to Reliability | 0.932 |
McDonald’s Omega | 0.903 |
Items of the MS-Q | Mean ± SD | MSQ-1 | MSQ-2 | MSQ-3 | MSQ-4 | MSQ-5 |
---|---|---|---|---|---|---|
MSQ-1 | 0.44 ± 0.50 | |||||
MSQ-2 | 0.25 ± 0.43 | 0.742 | ||||
MSQ-3 | 0.23 ± 0.42 | 0.623 | 0.683 | |||
MSQ-4 | 0.39 ± 0.49 | 0.613 | 0.631 | 0.708 | ||
MSQ-5 | 0.51 ± 0.51 | 0.598 | 0.595 | 0.571 | 0.731 |
Exploratory factor analysis
Number of Factors | Eigenvalue | Cumulative VAb | Above point of inflection on Scree plot | PA based on minimum rank | Decision to extract | |||||
---|---|---|---|---|---|---|---|---|---|---|
Real-data VEb | Mean of random VEb | 95th percentile of random VEb | Kaiser’s criteria (Eigenvalue≥1) | Cumulative VE rule (> 40%) | Scree test | PA 95th percentile of random VE > Real-data VE | ||||
1 | 3.599 | 71.982 | Yes | 88.8386b | 59.6842 | 76.9187 | a | a | a | a |
2 | 0.521 | 10.420 | No | 9.2623 | 32.3088 | 44.6539 | Χ | Χ | Χ | Χ |
3 | 0.409 | 08.185 | No | Χ | Χ | Χ | Χ |
Fit indices
Quality and effectiveness of factor score estimates, construct replicability and measures of closeness to unidimensionality
Internal consistency and item discrimination
Discriminative validity
Items of the MS-Q | Mean rank | U | p-value | |
---|---|---|---|---|
Attention complaints (n = 65) | No attention complaints (n = 238) | |||
MS-Q 1 | 174.90 | 145.75 | 6246.50 | .006 |
MS-Q 2 | 170.77 | 146.87 | 6515.00 | .010 |
MS-Q 3 | 161.78 | 149.33 | 7099.00 | .162 |
MS-Q 4 | 184.23 | 143.20 | 5640.00 | <.001 |
MS-Q 5 | 188.33 | 142.08 | 5373.50 | <.001 |
MS-Q total score | 189.57 | 141.74 | 5293.00 | <.001 |