Because researchers are not intervening for purposes of the study they can not control natural differences that could explain study findings so they can not prove a cause - and - effect relationship. (sciencedaily.com)
Therefore, the primary purpose of this study was to examine the effect of 6 weeks of abdominal exercises on abdominal fat in young adults. (journals.lww.com)
The main purpose of this study was to examine technology PD content and formats teachers perceived useful in 2009 and 2015, documenting whether shifts occurred. (citejournal.org)