Table 1.

Early versus late night comparison between group statistics using participant means and the linear mixed approach on individual spindles for several spindle characteristics.

		Spindle Parameter	duration	amplitude	globality	power	power (ratio)	frontal frequency	posterior frequency	log duration	log amplitude	log power	log power (ratio)
participant-mean	group paired T-test	Estimated Δ	174.722	−4.403	8.356	0.267	2.007	0.724	0.503	0.180	−0.151	0.043	0.157
		Standard Error	44.972	0.802	1.933	1.141	0.654	0.161	0.213	0.038	0.025	0.114	0.047
		Lilliefors Statistic	0.257	0.192	0.218	0.155	0.160	0.312	0.340	0.214	0.262	0.120	0.161
		t-value	−3.885	5.491	−4.323	−0.234	−3.069	−4.509	−2.358	−4.707	5.999	−0.375	−3.305
		p-value	0.005	0.001	0.003	0.821	0.015	0.002	0.046	0.002	0.000	0.717	0.011
individual spindles	linear mixed model	Estimated Δ	140.932	−5.139	7.224	1.139	2.659	0.483	0.362	0.130	−0.151	0.051	0.145
		Standard Error	8.044	0.221	0.283	0.208	0.187	0.027	0.026	0.008	0.006	0.012	0.009
		Lilliefors Statistic	0.079	0.111	0.036	0.167	0.150	0.048	0.133	0.032	0.022	0.028	0.029
		LR: Time of Night	304.351	531.280	640.101	30.003	200.271	307.317	195.006	291.753	666.878	16.559	256.858
		p-value	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000
		LR: Spindle Type	43.609	139.008	60.537	142.471	194.182	52.164	1357.156	64.187	140.091	180.752	212.561
		p-value	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000
		LR: Interaction	3.779	11.337	15.394	30.187	8.687	2.497	20.218	3.628	8.696	29.458	5.658
		p-value	0.151	0.003	0.000	0.000	0.013	0.287	0.000	0.163	0.013	0.000	0.059

The directly measured quantities as well as selected log-transformed versions are displayed. Estimated difference (Δ) indicates the particular model’s expected change in each parameter from an early to late NREM cycle, along with the standard error of that estimate. The Lilliefors statistic is a measure of the deviation from normality of the parameter distribution with values closer to zero being closer to the normal distribution. Likelihood ratio statistics (LR) and associated p-value are presented for the main effects of time of night (early versus late), the spindle type (frontal, posterior, and co-occurring), as well as the interaction, over-and-above just the model with additional terms. Note that the estimated differences change non-systematically; the distribution of individual spindles are almost always closer to the normal distribution (in the log-transformed cases, drastically lower); and that the mixed model always produces lower p-values.