Danielsoper statcalc calculator3/22/2023 The area below the normal curve represents a proportion or probability. Level of significance à the most commonly used one is 0.05 (5%)Į.- Suppose that a random variable x is normally distributed with mean μ and standard deviation sσ. your sample size is 30, then your df= 29ĭ. degree of freedom (df) à for paired sample t-test, df = sample size (N) – 1. critical t value à the value that we use to compare to our t computed, in order to find out if there is a statistically significant difference or notĬ. t computed: the t-value that you get from your calculationī. There are a few terms you need to know with when dealing with paired-sample t-test:Ī.The rules of thumb: If your t computed is larger than the critical t/ t-table and your probability (p) value is less than 0.05, you can conclude that the difference is statistically significant. Interpret your results and conclude whether there is a significant difference between the two sets of scores or not.However, if you want to get the result rather quickly- yet still very much accurately- we recommend using free online statistical tools such as VassarStats and Social Science Statistics (links are provided below). If you are a Math Geek, you might want to take your own sweet time and calculate manually by entering the values into the paired-sample t-test formula.Prepare your sets of scores (two sets of mean scores, no more and no less).n < 15), we should probably not use the t-test as the results may not be accurate. If we have a rather small sample size (e.g. It is all right to have more, but experts agree that ideally it should not be fewer than 25. In order to have a statistically reliable result, the number of scores in each set should be around 25- 30.When the two sets of scores come from two different groups of students, we use the independent-sample t-test.When the two sets of scores come from the same group of students (like in our example here), we use the paired-sample t-test.The t-test is used to compare two sets of scores in order to determine whether the average score (called the mean score) of the first set is significantly higher/lower than the second set.But how can you confidently say that the improvement is statistically significant? You need to perform a statistical test, called the t-test! We describe below the purpose and steps for running the t-statistic. At the end of the semester, you give them a similar test like the one you gave earlier.Īs you compare the test results, you notice that your students’ performance on the post-test is higher than on the pre-test. They speak more, they interact more with each other and their ability to express themselves in English seem to show improvement. On the first day of the semester, you give your students a test in order to get baseline data about their speaking ability.Īs you teach your students, you notice that your students seem to be more active and motivated. The following year, you put together a set of lesson plans based on the workshop ideas and teach your students for the whole semester. You find the ideas interesting and are thinking of trying out the teaching techniques with your students. You have just attended a one-day workshop on how to teach speaking skills more effectively.
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