# Inferential Statistics - Sample Errors occur when there is a difference between a sample and it's population - No two samples will be identical in all their chrarcteristics. - Distribution of sample means - if enough, you can predict for the larger population - Statistically significant ## Standard Error of the Mean - 68-95-99.7 rule ## Hypothesis Testing Hypothesis testing - Research hypothesis is - Null hypothesis is that there is nothing there One Tail test - Predicting a positive or negative result. Two tail test Predicting a If probability is small, reject the null hypothesis If the probably is large, do not rejec tthe null hypothesis - One's results are likely to occur ## Statistical significance - "Statistical significance means that one's results are likely to occur by chance less than a certain percentage of the time." - Statistical significance and practical significance are not necessarily the same since a result of statistical significance does not mean that it is practically significant in an educational sense. ## Type One vs. Type Two Errors - A null hypothesis predicts no relationship. - A **Type two** error results when the researcher fails to reject a null hypothesis that is false. - A **Type one** error results when the researcher rejects a null hypothesis when it is true. ## Excel - Excel can be used to randomize ## T Test - t-test for correlated means. - t-test for independent means.