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. Author manuscript; available in PMC: 2013 Jan 24.
Published in final edited form as: Am J Epidemiol. 2011 Sep 30;174(9):1077–1088. doi: 10.1093/aje/kwr243

Table 3.

Estimated Type I Error from the Wald Test (α̂ given in %) of Regression Parameter For Covariate X1 or X2 and Interaction With Time From 500 Replicated Samples of 500 Subjects in General Aging and Pre-Diagnostic Phase of Dementia.

Outcome distribution Estimated Model General Aging Pre-Diagnostic Phase of Dementia Sample
X1 X1× ta X2 X2 × ta X1 X1 × ta X2 X2 × ta
mim-MMSE Standard LMM 5.0 93.2b 33.6b 40.0b 4.8 97.8b 11.4b 54.0b
Pre-transformed LMM 3.6 40.8b 7.2b 13.0b 4.6 42.6b 6.0 13.0b
Beta LMM 4.4 4.6 4.0 4.2 4.4 6.2 4.6 6.0

mim-BVRT Standard LMM 3.2 21.4b 4.4 8.6b 4.6 12.2b 5.4 8.6b
Beta LMM 3.8 6.0 5.4 5.0 4.6 5.0 5.0 6.6

mim-IST Standard LMM 4.6 8.0b 6.6 4.8 4.2 6.0 6.2 5.6
Beta LMM 4.6 5.0 5.6 4.6 4.2 4.6 6.4 4.8

mim-CALC Standard LMM 5.0 45.6b 6.4 5.2 4.2 56.4b 26.0b 5.6
Threshold LMM 6.4 5.2 6.2 5.2 5.2 6.6 5.6 5.4

Abbreviations: LMM, Linear Mixed Model; mim-BVRT, distribution mimicking Benton Visual Retention Test; mim-CALC, distribution mimicking calculation subscore of MMSE; mim-IST, distribution mimicking Isaacs Set Test; mim-MMSE, distribution mimicking Mini-Mental State Examination; t, Time.

a

time t corresponds to age in decades from 65 in the general aging sample and years before diagnosis in pre-diagnostic phase of dementia sample.

b

estimated type I errors (α̂ ) outside the expected 95% interval 3.09, 6.91 around the nominal value of 5%.