VIZSGÁLATI ÉS KONTROLLCSOPORTOT EGY ADATFELVÉTELI ALKALOM ALAPJÁN ÖSSZEHASONLÍTÓ HATÁSVIZSGÁLATOK MATEMATIKAI STATISZTIKAI HÁTTERE

One kind of effectiveness study of developmental programs compares results of an experimental group and a control group (when the data collecting happened only once). This paper offers methodological guidance to choose, apply and interpret adequate mathematical statistic analysis of these studies. Using R environment (this is a downable free software) is recommended to compute statistical results.