How do researchers determine whether or not to reject the null hypothesis?

     A null hypothesis is a statement about a relation between populations that is the opposite of the research hypothesis (Aron, Aron, & Coupe, 2009). A research hypothesis is the exact opposite of a null hypothesis. In statistics, for one to support their hypothesis he or she must refute the null hypothesis. Instead of one proving their idea (alternate hypothesis) right, he or she needs to show that the null hypothesis is likely going to be wrong, as in to nullify or refute the null hypothesis ("Null Hypothesis", n.d.). One must assume his or her alternate hypothesis to be incorrect until they find contrary evidence. Researchers determine whether or not to reject the null hypothesis through the hypothesis-testing process. The hypothesis-testing process has five steps, which are (1) restate the question as a research hypothesis and a null hypothesis about the populations, (2) determine the characteristics of the comparison distribution, (3) determine the cutoff sample score on the comparison distribution at which the null hypothesis should be rejected, (4) determine your sample’s score on the comparison distribution, and (5) decide whether to reject the null hypothesis. The hypothesis-testing process is formal procedure used to accept or reject the null hypotheses. 

Reference

 Null Hypothesis. (n.d.). Retrieved from http://www.null-hypothesis.co.uk/science/item/what_is_a_null_hypothesis/

Aron, A., Aron, E. N., & Coups, E. (2009). Statistics for psychology (5th ed.). Upper Saddle River, NJ: Pearson Prentice Hall.