Table 1. The median illuminance and luminance levels on the chalkboard and student’s desk during morning and afternoon measurements.
| Variables | Morning (AM) | Afternoon (PM) | |||
|---|---|---|---|---|---|
| Median (IQR) | Range (minimum, maximum) | Median (IQR) | Range | AM and PM difference (p value) | |
| Chalkboard centre Illuminance (lux) | 104 (55, 175) | 23, 572 | 133 (70, 203) | 26, 490 | <0.001 |
| Uniformity index of chalkboard | 0.74 (0.56, 0.82) | 0.42, 0.91 | 0.71 (0.55, 0.79) | 0.19, 0.87 | 0.234 |
| Uniformity index of student’s desk | 0.56 (0.42, 0.68) | 0.27, 0.88 | 0.54 (0.38, 0.71) | 0.16, 0.82 | 0.449 |
| Luminance of chalkboard (Lbackground) Cd/m2 | 1.28 (0.95, 1.67) | 0.39, 28 | 1.43 (1.05, 1.92) | 0.61, 28 | 0.008 |
| Contrast level (Weber) | 40 (36, 50) | 20, 70 | 36 (30, 49) | 21, 59 | 0.088 |
IQR—Interquartile range. Descriptive information on the range is provided to present the maximum and the minimum limit of the variables