| Potential source of bias | Base-weighted respondent distribution | Final-weighted respondent distribution | |
|---|---|---|---|
| Public | |||
| Arizona, school level (secondary) | x | ||
| California, enrollment (500-749 students) | x | x | |
| California, school level (elementary and secondary) | x | x | |
| Colorado, school level (secondary) | x | ||
| Massachusetts, enrollment (500-749 students) | x | ||
| Michigan, school level (elementary) | x | ||
| Minnesota, enrollment (200-499 students) | x | x | |
| Minnesota, school level (elementary) | x | x | |
| Minnesota, school level (secondary) | x | ||
| National, enrollment (0-100 and 1000 or more students) | x | x | |
| National, enrollment (750-999 students) | x | ||
| National, locale (central city) | x | x | |
| National, locale (rural) | x | ||
| National, school level (secondary and combined) | x | x | |
| Nebraska, school level (combined) | x | ||
| State (California) | x | ||
| Texas, school level (elementary) | x | ||
| Virginia, locale (suburban) | x | ||
| Washington, school level (secondary) | x | ||
| Wyoming, enrollment (200-499) | x | ||
| Wyoming, school level (secondary) | x | ||
| BIE | |||
| National, region (all other states) | x | ||
| NOTE: x denotes comparisons that are a potential source of bias. BIE refers to schools funded by the Bureau of Indian Education that are operated by the BIE, a tribe, or a private contractor and not by a regular school district. | |||
| SOURCE: U.S. Department of Education, National Center for Education Statistics, Schoolsand Staffing Survey (SASS), "Public School Library Media Center and BIE School Library Media Center Data Files," 2007–08. | |||
