Does pattern mixture modelling reduce bias due to informative attrition compared to fitting a mixed effects model to the available cases or data imputed using multiple imputation?: a simulation study

Table 4 Correlations among variables in full simulated memory cognitive score data and differences compared to correlations among variables in available case analyses data, data imputed using multiple imputation and after applying pattern mixture modelling

		Memory cognitive function			Smoking status			Age	Grade	Education
	Phase	5	7	9	5	7	9	5	5	5
Full simulated data	Mem 5	1
	Mem 7	0.4419	1
	Mem 9	0.4423	0.4458	1
	Smoke 5	−0.0806	−0.0884	−0.1041	1
	Smoke 7	− 0.0715	− 0.0800	− 0.0948	0.9616	1
	Smoke 9	−0.0636	−0.0764	− 0.0902	0.9337	0.9592	1
	Age	−0.2729	− 0.3127	− 0.3379	0.0281	0.0369	0.0451	1
	Grade	−0.2404	− 0.1913	− 0.1660	0.0983	0.0881	0.0817	−0.0501	1
	Education	0.2058	0.1919	0.1779	−0.1114	− 0.1043	− 0.1005	− 0.0784	− 0.3691	1
Differences^a in correlations from those above
Available case	Mem 5	0
	Mem 7	0.0355	0
	Mem 9	0.0544	0.0630	0
	Smoke 5	0.0159	0.0029	0.0040	0
	Smoke 7	0.0071	0.0032	0.0004	0.0009	0
	Smoke 9	0.0137	−0.0005	0.0050	0.0025	0.0087	0
	Age	−0.1632	− 0.1679	− 0.2154	− 0.0253	− 0.0237	− 0.0194	0
	Grade	−0.0120	− 0.0102	− 0.0125	0.0066	0.0043	0.0004	−0.0104	0
	Education	0.0052	0.0032	0.0339	−0.0050	− 0.0022	0.0015	− 0.0151	− 0.0031	0
Multiple imputation	Mem 5	0
	Mem 7	0.0157	0
	Mem 9	0.0970	0.0364	0
	Smoke 5	0.0528	0.0579	0.0306	0
	Smoke 7	0.0522	0.0550	0.0360	0.0062	0
	Smoke 9	0.0532	0.0506	0.0377	0.0083	0.0080	0
	Age	−0.0186	−0.0298	− 0.0269	− 0.1200	− 0.1246	− 0.1237	0
	Grade	0.0067	− 0.0012	− 0.0070	− 0.0116	− 0.0145	− 0.0079	0	0
	Education	− 0.0067	0.0169	0.0066	0.0282	0.0272	0.0329	0	0	0
Pattern mixture modelling	Mem 5	0
	Mem 7	0.0115	0
	Mem 9	0.0877	0.0099	0
	Smoke 5	0.0528	0.0675	0.0410	0
	Smoke 7	0.0522	0.0655	0.0464	0.0062	0
	Smoke 9	0.0532	0.0612	0.0481	0.0083	0.0080	0
	Age	−0.0186	− 0.0204	− 0.0194	− 0.1200	− 0.1246	− 0.1237	0
	Grade	0.0067	0.0020	0.0007	−0.0116	− 0.0145	− 0.0079	0	0
	Education	−0.0067	0.0123	−0.0001	0.0282	0.0272	0.0329	0	0	0

^aDifferences in correlations are calculated as correlation in analysis type minus correlation in full simulated data

ISSN: 1471-2288