A type i error is committed when

a. a true null hypothesis is rejected

b. sample data contradict the null hypothesis

c. the critical value is greater than the value of the test statistic

d. a true alternative hypothesis is not accepted

Answer: Choice A) A true null hypothesis is rejected

In other words, if the reality is that the null is true but your research says otherwise, then you've committed a type i error.

A type ii error is when you fail to reject the null (basically "accepting" the null) while in reality the alternative is the true hypothesis.