Example 16.2, table 16.1 in Sedlmeier & Renkewitz (2018). Fictitious data set with 15 boys divided into three groups (no training, boys-specific material, girls-specific training material). The DV is the number of solved problem (similar to the training).
data(sedlmeier_p525)
a data frame with 15 rows and 3 columns
dv, number of solved exercises
group, KT=no training, JT=boys-specific, MT=girls-specific
lambdas used for this example