Datasets used in publication "Mu-opioid receptor-dependent changes in social reward across adolescence in mice" (in preparation). The social conditioned place preference data were pre-processed before statistical analysis. Three diffrent datatables with the same dataset reflect the steps of the pre-processing: 1. Animals that spent more than 70% of the pretest time in one of the contexts were excluded (datable "30_70%") 2. Outliers were identified using Grubbs test, and removed (datatable "no_outlier") 3. In cases where the final number of animals conditioned in each context was not equal (due to an unequal number of animals passing the 70% criterion or unequal number of animals in the litter), we pseudorandomly trimmed the larger group using a Python script (file number 10). The exception from completely random selection was introduced to preserve a mean 50% initial context preference during the pretest