Question

what conclusion can be drawn from a study with a null result

Answer 1

Solution:

• A null result occurs when we fail to reject . This is commonly referred to as a non-significant result or n-s. There are two possible “realities” when the null is not rejected.
• First, is the case where the null is true. If were true, the probability of failing to reject is .95.
• When the null is true, it is unlikely to make a Type I error. Second, is the situation wherein is false but we fail to reject . This reflects the Type II error probability (1 - Power).
• If the null is actually false, this probability is ideally about .20. This means that, given an ideal situation, when is false it will not be rejected 1 out of 5 times. This result does not convey statistical certainty.
• It is likely that either is true or is false. Neither result is ruled unlikely. This differs sharply from situations wherein we can reject . When we reject , there is a comparatively small probability that we have made an error (i.e., Type I error rate of 5%).