Data Analysis Inferential Statistics Statistics measure the sample.
Parameters measure the population.
Inferences are made about the parameters from the statistics. If the probability that the statistic would appear by chance given a true hypothesis is less than a , then the hypothesis is rejected. The statistic is outside the interval where it would appear by chance more than 5 times out of 100 or 1 time out of 100. The chance that the difference was do to random chance is so small that the difference must be real. Research studies test the null hypothesis there is no difference.