mixmeta (version 1.2.0)

school: Studies on Modified School Calendar and Student Achievement

Description

The dataset contains the results of 56 studies that evaluate the effect of a modified school calendar on student achievement. The studies assessed students from grade 1 to 9 and reported standardized reading achievement differences between schools that follow a year-round versus the traditional nine-month calendar. The studies were performed in separate school districts, with at least three studies in each district.

Usage

school

Format

A data frame with 56 observations on the following 5 variables:

• district, study: numbers identifying the school district and study, respectively.

• effect: estimated standardized effect, reported as difference in reading achievement expressed in standard deviation units.

• var: within-study variance of the estimated effects.

• year: year when the study was performed.

Examples

# NOT RUN {
### REPRODUCE THE RESULTS IN KOSTANTOPOULOS (2011), TABLES 4 AND 5

# STANDARD META-ANALYSIS (NB: random NOT STRICTLY NEEDED HERE)
mod1 <- mixmeta(effect, var, random= ~ 1|study, data=school, method="ml")
print(summary(mod1), digits=3, report="var")

# STANDARD META-REGRESSION
yearcen <- school$year - mean(school$year)
mod2 <- mixmeta(effect ~ yearcen, var, random= ~ 1|study, data=school,
  method="ml")
print(summary(mod2), digits=3, report="var")

# TWO-LEVEL META-ANALYSIS
mod3 <- mixmeta(effect, var, random= ~ 1|district/study, data=school,
  method="ml")
print(summary(mod3), digits=3, report="var")

# TWO-LEVEL META-REGRESSION
yearcen2 <- with(school, year - mean(tapply(year, district, mean)))
mod4 <- mixmeta(effect ~ yearcen2, var, random= ~ 1|district/study, data=school,
  method="ml")
print(summary(mod4), digits=3, report="var")

### SEE help(thrombolytic) FOR A COMPLEMENTARY EXAMPLE
# }