The tenth, eleventh, twelfth, thirteenth sessions The key points we leaed in the very last sessions are as following: If the numbers are below ten, we should write them in words and if the numbers are above ten, we should write them in numbers. If I have 1000 students and then I hold a test in which 500 students only fit the intermediate level and then I choose all those 500 students, my sampling will be purposive, but if among all those 500 students, I choose 100 of them randomly, then I will have a real random sampling. If I only have girls students and I have to only work with that group, this is called limitation of my study. But if I myself want to only work with female students, not male students in my study, then it will be delimitation. In a study we can have two pre- tests. One that is supposed to homogenize the participants. For example, I hold the PET test and I only choose intermediate students. Then I can have another pre- test related to the purpose of my study. For example, If my study is about vocabulary, I hold a pre- test to measure my students' vocabulary knowledge at the begiing of the study. A word of caution, if the scores of the second pre- test are controlled we can use SPANOVA to analyse the data and if the pre- test results are not controlled, we should use ANCOVA. Using t-test, we should notice that data must be interval. If we have frequency type data, then we should use chi- square. What is informed consen