## US Sustaining Effects study

### Description

A subset of the mathematics scores from the U.S. Sustaining Effects
Study. The subset consists of information on 1721 students from 60 schools

### Usage

`data(egsingle)`

### Format

A data frame with 7230 observations on the following 12 variables.

- schoolid
a factor of school identifiers

- childid
a factor of student identifiers

- year
a numeric vector indicating the year of the test

- grade
a numeric vector indicating the student's grade

- math
a numeric vector of test scores on the IRT scale score metric

- retained
a factor with levels `0`

`1`

indicating if
the student has been retained in a grade.

- female
a factor with levels `Female`

`Male`

indicating the student's sex

- black
a factor with levels `0`

`1`

indicating if
the student is Black

- hispanic
a factor with levels `0`

`1`

indicating if
the student is Hispanic

- size
a numeric vector indicating the number of students
enrolled in the school

- lowinc
a numeric vector giving the percentage of low-income
students in the school

- mobility
a numeric vector

### Source

These data are distributed with the HLM software package (Bryk,
Raudenbush and Congdon, 1996). Conversion to the R format is
described in Doran and Lockwood (2004).

### References

Doran, Harold C. and Lockwood, J.R. (2004), *Fitting value-added
models in R*, (submitted).

### Examples

```
str(egsingle)
(fm1 <- lmer(math~year*size+female+(1|childid)+(1|schoolid), egsingle))
```