4/10/2024 0 Comments Calculate degree of freedom t test![]() ![]() ![]() The null hypothesis assumes that the known mean is correct. The one-sample t-test checks if the known mean is statistically correct, based on a sample average and sample standard deviation. One-sample t-test ( go to the calculator) What is the one-sample t-test? The higher the degree of freedom the more it resembles the normal distribution. The shape depends on the degrees of freedom which is usually the number of independent observations minus one (n-1). This makes it more realistic than Normal distribution since for small sample sizes, the average and standard deviation estimations are less accurate T distribution looks similar to the normal distribution but lower in the middle and with thicker tails. Student's T distribution is an artificial distribution used for a normally distributed population when we don't know the population's standard deviation. When the sample is greater than 30 you should still use the t-distribution, although using the normal distribution instead will support similar results. When we know the standard deviation value, for example from another research, we use the z-test, but usually, we have only the sample standard deviation. We use the t-test(s) to compare the sample average (Mean) to the known mean or to compare the averages of two groups when we don’t know the standard deviation, and use the sample standard deviation. The t-test is not one test, but a group of tests that constitutes all statistical tests distribute as t-distribution (Student’s t-distribution). ![]()
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