The effect of high correlated colour temperature office lighting on employee wellbeing and work performance

Table 2 Distribution of Modified Columbia Scale scores examined by group and time period.

		Baseline		Study End (3 months)		% change		Unpaired t test (df = 67)	Paired t test (df = 22)	Paired t test (df = 45)	Unpaired t test (df = 67)
Item No.	Description	Control (n = 23)	Intervention (n = 46)	Control (n = 23)	Intervention (n = 46)	Control	Intervention	Baseline comparison	Control change	Intervention change	3 month comparison
		mean (SD)	mean (SD)	mean (SD)	mean (SD)			t statistic	t statistic	t statistic	t statistic
1	Fatigue/tiring easily?	2.9 (0.9)	2.9 (1.1)	2.7 (1.1)	2.1 (1.0)	7.6	26.9	-0.16	0.93	4.04**	1.76
2	Trouble concentrating	2.5 (1.1)	2.9 (1.2)	2.5 (0.9)	1.8 (0.9)	1.7	36.8	-1.23	0.21	5.84**	3.46*
3	Physical clumsiness?	2.0 (1.1)	1.7 (1.0)	1.6 (0.6)	1.5 (0.9)	21.7	13.7	1.02	1.93	1.48	-0.70
4	Decreased daytime alertness?	2.7 (1.1)	2.5 (1.2)	2.1 (0.8)	1.8 (0.8)	21.0	28.1	0.74	2.73	3.96**	0.45
5	Trouble with memory?	2.4 (1.3)	1.9 (1.1)	2.1 (0.8)	1.5 (0.7)	12.5	21.3	1.65	1.07	2.80	0.38
6	General feelings of weakness	2.0 (1.1)	2.0 (1.0)	1.7 (0.7)	1.4 (0.8)	17.0	26.7	0.33	1.56	3.60*	0.67
7	Light-headed & dizzy	2.2 (1.4)	2.1 (1.3)	2.0 (1.1)	1.4 (0.8)	9.8	33.7	0.26	1.10	4.04**	1.74
8	Lethargy/sluggish feelings?	3.0 (1.0)	2.7 (1.3)	2.3 (0.8)	1.8 (0.8)	23.5	31.7	0.93	3.43*	5.07**	0.55
9	Sleepiness in day	3.0 (1.2)	2.8 (1.2)	2.6 (1.0)	1.9 (0.7)	14.5	31.0	0.66	2.47	4.90**	1.55
10	Work performance	7.0 (1.7)	6.4 (1.5)	7.3 (1.6)	7.6 (1.4)	4.4	19.4	1.45	-1.16	-6.07**	-2.72
11	Alertness and concentration	6.2 (1.8)	6.1 (1.9)	6.8 (1.7)	7.5 (1.8)	9.9	22.9	0.23	-2.13	-4.34**	-1.57
	Combined Score (first 9 items)	22.7 (7.5)	21.5 (8.3)	19.5 (5.2)	15.4 (5.7)	14.3	28.6	0.59	2.60	5.22**	1.53