Rasch modelling to deal with changes in the questionnaires used during long-term follow-up of cohort studies: a simulation study

Table 1 Performance criteria of the LCGA applied to the various measures of the subjective phenomenon

Criterion	Scenario	LCGA-S	LCGA-stS	LCGA- θ_est	LCGA- θ_sim
%CC	Complete	77.5 [77.3 – 77.6]	77.6 [77.4 – 77.7]	75.7 [75.5 – 75.8]	82.3 [82.2 – 82.4]
	7 items - Difficult	76.3 [76.1 – 76.4]	77.2 [77.1 – 77.3]	75.1 [74.9 – 75.2]
	7 items - Easy	73.7 [73.6 – 73.9]	76.7 [76.6 – 76.8]	75.0 [74.8 – 75.1]
	4 items	72.8 [72.7 – 72.9]	76.3 [76.2 – 76.5]	74.3 [74.1 – 74,4]
Kappa	Complete	0.662 [0.660 –0.664]	0.664 [0.661 –0.666]	0.635 [0.633 –0.637]	0.734 [0.732 – 0.736]
	7 items - Difficult	0.644 [0.642 –0.646]	0.658 [0.656 –0.660]	0.626 [0.624 –0.628]
	7 items - Easy	0.606 [0.603 –0.609]	0.651 [0.649 –0.653]	0.624 [0.622 –0.627]
	4 items	0.592 [0.590 –0.594]	0.645 [0.643 –0.647]	0.614 [0.612 –0.616]
Entropy	Complete	0.775 [0.774 –0.776]	0.775 [0.774 –0.776]	0.755 [0.754 –0.756]	0.909 [0.909 – 0.910]
	7 items - Difficult	0.734 [0.733 –0.736]	0.761 [0.760 –0.762]	0.741 [0.740 –0.742]
	7 items - Easy	0.730 [0.729 –0.732]	0.761 [0.760 –0.762]	0.740 [0.738 –0.741]
	4 items	0.655 [0.653 –0.657]	0.744 [0.743 –0.745]	0.723 [0.721 –0.724]

Legend: %CC: mean proportion of correctly classified subjects, LCGA: latent class growth analysis, S: raw score, stS: standardised score, θ_est: latent variable score estimated by the Rasch model, θ_sim: simulated latent variable, [95 % confidence interval]

ISSN: 1471-2288