Two sample t test for difference of means by Khan Academy
In this video, a problem about Kaito growing tomatoes in two separate fields is introduced. Kaito wonders if the sizes of the tomato plants differ between the two fields so he took a random sample from each and showed the number, mean, and standard deviation for each. The problem wants to find out if there is actually a difference in the size of the tomato plants at a a=0.05 level of significance. In order to do this, a 2 sample t test is used. First, the null and alternate hypotheses are stated. Then, the t value is found to be -2.44 using the difference in means between fields A and B. A tcdf tool is then used to find the p value, but it must be multiplied by two since this is a two-tailed test, so p=0.024. Then, since p is less than a, we can reject the null hypothesis and suggest Ha.
I feel that this video enhances my learning on this topic because it’s easy to look at an example and not know exactly why a graph was drawn the way it was or how/where they got a certain number from, but this video does a very nice step by step example that explains everything! In my experience with statistics, t-tests are something that a lot of students need extra help with, especially two tailed. This video definitely supplements the information gone over in class, and provides an extra example that can be easily understood. In my opinion, the best thing about this video is they show how to draw the t-graph for a two-tailed test! Seeing them draw the graph and listening to the reasoning really drives the entire point of a two-tailed test home. An added bonus – this video can be replayed as many times as needed, or paused to follow along. This video is an important tool that can be used to supplement learning about two tailed t tests in statistics.
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