PSY30100 Lecture Notes - Lecture 9: Null Hypothesis, Type I And Type Ii Errors, Statistical Hypothesis Testing
Document Summary
Suppose the population mean =80 before treatment and sample mean m=85 after treatment. The difference in and m may not have been caused by the treatment. Since hypothesis testing depends on sample statistics, it is vulnerable to sampling errors. Hence, there is always the chance that the hypothesis test is wrong. Probability of type i error = p of level. The chance of a type i error occurring can be controlled to some degree since it is dependent on our criteria for accepting or rejecting h0. The larger the level, the higher the chance that sampling error caused a difference in means. Probability of type ii error (cid:2869) sample size. The chances of type ii error occurring increase with decrease in sample size. The treatment may have a significant effect but the sample size is too small for it to be observable.
