Fixed and Random Effects for Group Comparisons on WM and Short-Term Memory Tasks (HLM Full Models)

	Listening Recall					Counting Recall					Digit Recall					Block Recall
Fixed Effects	Coefficient	SE	T-ratio	p	Fixed Effects	Coefficient	SE	T-ratio	p	Fixed Effects	Coefficient	SE	T-ratio	p	Fixed Effects	Coefficient	SE	T-ratio	p
Model 1a					Model 2a					Model 3a					Model 4a
Intercept	7.39	0.56	13.15	0.00	Intercept	13.97	0.94	14.81	0.00	Intercept	23.73	0.56	42.34	0.00	Intercept	18.93	0.76	24.90	0.00
Strategy vs. Control	1.50	0.67	2.25	0.03	Strategy vs. Control	0.95	1.25	0.76	0 .46	Strategy vs. Control	−0.82	0.76	− 1.07	0.29	Strategy vs. Control	−0.01	1.08	−0.01	0.99
No - strategy vs. Control	0.49	0.67	0.74	0.47	No - strategy vs. Control	1.76	1.26	1.40	0 .17	No- strategy vs. Control	−0.57	0.77	− 0.74	0.46	N o- strategy vs. Control	0.79	1.10	0.71	0.48
Pre-Listening Recall	0.57	0.09	6.25	0.00	Pre-Counting Recall	0.29	0.12	2.31	0.03	Pre-Digit Recall	0.72	0.08	8.71	0.00	Pre-Block Recall	0.79	0.11	7.47	0.00
Model 1b					Model 2b					Model 3b					Model 4b
Intercept	7.88	0.56	13.98	0.00	Intercept	15.73	0.96	16.45	0.00	Intercept	23.16	0.57	40.49	0.00	Intercept	19.72	0.78	25.36	0.00
Strategy vs. No-strategy	1.01	0.67	1.52	0.14	Strategy vs. No-strategy	−0.81	1.26	−0.64	0.52	Strategy vs. No-strategy	−0.25	0.77	−0.32	0.75	Strategy vs. No-strategy	−0.79	1.09	−0.73	0.47
Control vs. No-strategy	−0.49	0.67	−0.74	0.47	Control vs. No-strategy	−1.76	1.26	−1.40	0.17	Control vs. No-strategy	0.57	0.77	0.74	0.46	Control vs. No-strategy	−0.78	1.10	−0.71	0.48
Pre-Listening Recall	0.57	0.09	6.25	0.00	Pre-Counting Recall	0.29	0.12	2.31	0.03	Pre-Digit Recall	0.72	0.08	8.71	0.00	Pre-Block Recall	0.79	0.11	7.47	0.00
Random Effects	School level variance	Student level residual variance	χ2	BIC	Random Effects	School level variance	Student level residual variance	χ2	BIC	Random Effects	School level variance	Student level residual variance	χ2	BIC	Random Effects	School level variance	Student level residual variance	χ2	BIC
	1.15	4.15	26.14*	262.48		1.34	14.99	17.24	327.21		0.33	5.60	13.31	272.66		0.01	11.17	10.09	307.52

Note. Coefficient = Unstandardized coefficient in HLM models, the mean difference between study groups adjusted for level-1 covariates; SE = Standard Errors of the coefficient, BIC = Bayesian Information Criterion. Models 1a~4b represent the comparison of “Strategy vs. Control” and “No-strategy-instruction vs. Control”. Because of Dummy coding, the Random Effects are the same for Model 1a and 1b, Model 2a and 2b, Model 3a and 3b, and Model 4a and 4b.

All coefficients in HLM models became non-significant after application of the Benjamini–Hochberg correction of p values for multiple comparisons (i.e., p < .01).

^*p < .05,

⁺p < .08.