Table 1.
Comparison of recorded and self-reported means for phone related variables.
| Variables of Interest Paired in Self-Report vs. Recorded | Mean and Standard Devitation (Median and Interquartile Range) | Significance Test (Wilcoxon Signed Rank Test) |
|---|---|---|
| Self-reported weekly phone use (N = 58) | 15.79 (SD = 18.04) (10.00 (IR = 13.50)) | z = −1.90, p = 0.06 |
| Recorded weekly phone use (N = 58) | 10.16 (SD = 6.06) (9.51 (IR = 8.65)) | |
| Self-reported incoming calls each week (N = 58) | 3.83 (SD = 3.62) (3.00 (IR = 4.00)) | z = −4.43, p < 0.01 * |
| Recorded incoming calls each week (N = 58) | 6.55 (SD = 5.10) (5.25 (IR = 6.14)) | |
| Self-reported outgoing calls each week (N = 58) | 3.72 (SD = 3.70) (2.75 (IR = 3.25)) | z = −6.45, p < 0.01 * |
| Recorded outgoing calls each week (N = 58) | 14.31 (SD = 10.35) (10.75 (IR = 13.53)) | |
| Self-reported incoming SMS each week (N = 58) | 9.30 (SD = 6.12) (9.00 (IR = 8.75)) | z = −3.79, p < 0.01 * |
| Recorded incoming SMS each week (N = 58) | 24.05 (SD = 27.52) (16.28 (IR = 20.46)) | |
| Self-reported outgoing SMS each week (N = 44) | 10.72 (SD = 9.86) (9.00 (IR = 10.75) | z = −0.76, p = 0.22 + |
| Recorded outgoing SMS each week (N = 58) | 17.83 (SD = 26.37) (10.26 (IR = 16.29) | |
| Recorded outgoing SMS each week (N = 44) | 18.40 (SD = 26.38) (11.24 (IR = 16.12) |
Note: * holds for multiple testing after Bonferroni adjustment (α = 0.05 divided by five tests = α = 0.01); + as the Wilcoxon signed rank test requires same sample sizes we built a second group for the last variable consisting out N = 44 instead of N = 58.