Table 1.

Descriptive statistics for full (N=4,229 students) and study samples (N=3,306 students)

	Full sample			Study sample
	obs.	mean/ %	SD	obs.	mean/ %	SD	p-value of difference
Gender
Male	2,051	48.5%		1,593	48.2%		0.48
Race/ethnicity
White	423	10.0%		331	10.0%		0.96
Hispanic	2,888	68.3%		2,226	67.3%		0.01*
Vietnamese	571	13.5%		470	14.2%		0.01*
Other	351	8.30%		281	8.50%		0.38
Free/reduced lunch (NSLP) and English Learner (EL) status
NSLP status	3,180	75.2%		2,474	74.8%		0.15
EL status	2,051	48.5%		1,587	48.0%		0.33
Prior math achievement (CST scaled score)
7th grade	4,229	337	60.6	3,306	341	60.7	0.00***
Prior math achievement bins
High achievement	1,594	37.7%		1,302	39.4%		0.00***
Average achievement	1,362	32.2%		1081	32.7%		0.10
Low achievement	1,273	30.1%		922	27.9%		0.00***
8th grade motivational measures, Fall
Mastery	3,500	3.71	0.92	3,089	3.73	0.91	0.00***
Performance approach	3,522	2.49	1.06	3,101	2.50	1.06	0.18
Performance avoid	3,560	2.44	1.01	3,083	2.43	1.01	0.12
Self-efficacy	3,525	3.32	0.89	3,103	3.34	0.87	0.01**
Task value	3,531	3.44	0.64	3,108	3.46	0.64	0.00***
8th grade motivational measures, Spring
Mastery	3,602	3.50	1.00	3,273	3.50	1.00	0.25
Performance approach	3,630	2.21	0.99	3,297	2.18	0.98	0.00***
Performance avoid	3,619	1.94	0.91	3,289	1.91	0.98	0.00***
Self-efficacy	3,636	3.23	0.94	3,302	3.24	0.90	0.02*
Task value	3,636	3.31	0.66	3,303	3.31	0.66	0.46

Note. Motivation scales = 1 – 5; Math scale score range = 150 – 600, 150-256 = Far Below Basic, 257-299 = Below Basic, 300-349 = Basic, 350-413 = Proficient, 414-600 = Advanced; Free/reduced lunch (NSLP) and English Learner (EL) status scale = 0-1 (1 = yes, 0 = no). Prior achievement bins: high achievement = Proficient or Advanced; average achievement = Basic; low achievement = Below Basic or Far Below Basic.