Probability levels and errorsA decision that must be made at the beginning of your dissertation research involves probability levels and potential errors. The conventional levels for rejecting the null hypothesis are either .05 or .01. One (.01) is more conservative than the other (.05) because with .01 you are less willing to have your results due to chance alone. You will accept only one time in one hundred that your results were due to chance. A really conservative probability level is .001. 1. A Type I (Alpha) Error occurs when you reject the null and it was actually true. We conclude falsely that there were differences when there was none. 2. A Type II (Beta) Error occurs when you accept the null and it was in fact false. We conclude that there are no differences when in fact there were! If the hypothesis is true, you accept the null. If the hypothesis is false, you reject the null.
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