It’s a new day – is it? Testing accumulation and sensitisation effects of workload on fatigue in daily diary studies

Figures & data

Figure 1. Theoretical model on the proposed relations between workload and fatigue within and across days.

Table 1. Measures for the four studies.

	Sample 1	Sample 2	Sample 3	Sample 4
Day-specific workload
Source	Semmer et al. (1995)	Semmer et al. (1995)	Semmer et al. (1995)	Semmer et al. (1995)
Number of items	3	3	3	3
Scaling	1 (not at all) to 5 (to a very great extent)	1 (not at all) to 5 (to a very great extent)	1 (not at all) to 5 (to a very great extent)	1 (not at all) to 5 (to a very great extent)
Measurement occasion	Afternoon	Afternoon	End of work	End of work
Reliability (Omega)	.82	.86	.84	.85
Day-specific fatigue
Source	Van Hooff et al. (2007)	Frone and Tidwell (2015)	Cranford et al. (2006)	Cranford et al. (2006)
Number of items	1	3	3	3
Scaling	1 (not at all fatigued) to 5 (extremely fatigued)	1 (not at all) to 5 (very strongly)	1 (not at all) to 5 (very much)	1 (not at all) to 5 (very much)
Measurement occasions	End of work	End of work	End of work	End of work
Reliability (Omega)	–	.80	.86	.86

Table 2. Fictitious example of workload pile-up index across study observation period (2 weeks).

ID	Day	Week	Workload	Workload centred	Calculation pile-up index	Workload pile-up index
1	Mon	1	4	−0.5	n/a	n/a
1	Tue	1	4	−0.5	=(−.50*1)	− 0.5
1	Wed	1	4	−0.5	=(−.50*1) + (−.50*2)	− 1.5
1	Thu	1	4.5	0	=(−.50*1) + (−.50*2) + (−.50*3)	− 3.0
1	Fri	1	4.5	0	=(−.50*1) + (−.50*2) + (−.50*3) + (0*4)	− 3.0
1	Mon	2	4.5	0	n/a	n/a
1	Tue	2	4.5	0	=(0*1)	0
1	Wed	2	5	0.5	=(0*1) + (0*2)	0
1	Thu	2	5	0.5	=(0*1) + (0*2) + (.50*3)	1 .5
1	Fri	2	5	0.5	=(0*1) + (0*2) + (.50*3) + (.50*4)	3 .5

Table 3. Means, standard deviations, and correlations for study variables.

	M	SDw	SDb	ICC	1	2	3
Sample 1
1. Workload	2.42	0.80	0.78	.49	–	.17*	.41*
2. Workload pile-up index	0.21	2.51	0.12	<.01	−.09	–	.11
3. Fatigue	2.63	0.80	0.58	.34	.19*	−.02	–
Sample 2
1. Workload	2.27	0.66	0.92	.66	–	.01	.55*
2. Workload pile-up index	0.06	2.05	0.09	<.01	.04	–	<.01
3. Fatigue	2.43	0.62	0.91	.68	.09*	−.01	–
Sample 3
1. Workload	2.24	0.84	0.80	.48	–	−.09	.28*
2. Workload pile-up index	0.06	2.40	0.14	<.01	−.08	–	−.06
3. Fatigue	2.17	0.71	0.68	.48	.19*	−.03	–
Sample 4
1. Workload	2.39	0.86	0.71	.40	–	.07	.57*
2. Workload pile-up index	−0.02	2.48	0.16	<.01	.04	–	.02
3. Fatigue	2.42	0.77	0.74	.48	.28*	.15*	–

Notes: Correlations below the diagonal reflect the within-person associations of the constructs. Correlations above the diagonal reflect the between-person associations of the aggregated measures. SD_w = within-person standard deviation; SD_b = between-person standard deviation; ICC = intraclass correlation (proportion of the between-person variance compared with the total variance).

*p < .05 (two-tailed testing). For clarity, no further differentiation between p-values below .05 is shown in this and subsequent tables.

Table 4. Unstandardised regression coefficients and standard errors predicting daily fatigue (samples 1–4).

Model	1: within day		2: accumulation across week		3: sensitisation across week
	Est.	SE	Est.	SE	Est.	SE
Day	.01/.01/−.01/−.01	.04/.01/.07/.01	.01/.01/−.01/−.01	.01/.01/.01/.01	.01/.01/−.01/−.06	.01/.01/.01/.01
Sine	.04/.06*/.03/−.01	.04/.03/.03/.03	.03/.06/.05/.01	.04/.03/.04/.04	.03/.05/−.05/.01	.04/.04/.05/.04
Cosine	−.09*/.01/−.02/.06	.05/.03/.04/.03	−.16*/−.03/−02/−.03	.08/.06/.07/.07	−.16*/−.03/−.02/.−.03	.08/.06/.07/.07
Workload (WL)	.18*/.08*/.15*/.24*	.04/.03/.04/.03	.23*/.09*/.18*/.24*	.05/.04/.05/.05	.23*/.09*/.18*/.24*	.05/.04/.05/.05
WL pile-up			.01/−.01/−.01/.04	.01/.01/.02/.01	.01/−.01/−.01/.04*	.01/.01/.02/.01
Interaction^a					<.01/<.01/.02/.01	.04/.03/.02/.06
Residual variance L1	.34*/.34*/.46*/.48*	.05/.03/.04/.04	.37*/.35*/.49*/.41*	.06/.04/.06/.04	.37*/.34*/.49*/.41*	.06/.04/.06/.04
Residual variance L2	.59*/.84*/.48*/.56*	.04/.07/.07/.07	.54*/.82*/.48*/.59*	.05/.09/.10/.08	.53*/.83*/.48*/.59*	.06/.09/.10/.08
AIC	2787.9/3214.9/2203.9/3285.3		1908.0/2087.3/1507.5/1992.0		1913.7/2090.9/1511.4/1993.0
BIC	2832.9/3262.5/2247.4/3332.2		1963.3/2145.0/1560.3/2048.3		1982.8/2163.0/1577.4/2063.4

Note: Est. = unstandardised regression coefficient, SE = standard error, AIC = Akaike information criterion, BIC = Bayesian information criterion. ^a Interaction of current workload and workload pile-up.

* p < .05 (two-tailed testing).

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