Introduction Hypothesis Testing using T-test
The t-test tells you how significant the differences between groups. It means that it lets you know if those differences (measured in means/averages) could have happened by chance.
What Is Mean By Hypothesis Testing using T-test?
The T-Test is ratio of the difference between the two groups and the difference within the groups. The larger the t score, the more difference there is between groups. The smaller the t score, the more similarity there is between groups. A t-score of 4 means that the groups are four times as different from each other as they are within each other. When you run a t-test, the bigger the t-value, the more likely it is that the results are repeatable.
Types of T-test
There are three main types of t-test:
- An independent sample t-test
- A Paired sample t-test
- A One sample t-test
A Paired sample-test
A paired t-test also called a paired samples t-test or dependent samples t-test. Where you run a t-test on dependent samples. Dependent samples are essentially connected.
- MRI costs at two different hospitals,
- Two tests on the same person before and after training,
- Two sugar measurements on the same person using different equipment.
- When choosing t-test:
Choose the paired t-test if you have two measurements on the same item, person, or thing. You should choose a t-test when you measure anything that is unique condition.
For Example: measuring a metal strength. Although the manufacturers are different, you might be subjecting them to the same conditions. Two sample t-test it means you comparing two different samples.
Another Example: test two different groups, means-testing an interview from the company. If you take a random sampling from each group separately and they have different conditions, then samples are independent and should run independent samples t-test.
In hypothesis testing, the independent sample t-test is μ1 = μ2. It means, assumes the means are equal. With the paired t-test, the null hypothesis is that the pairwise difference between the two tests is equal (H0: µd = 0).
- Steps of t-test:
Step 1: Subtract each Y score from each X score.
Step 2: Add up all of the values from Step 1.
Set this number aside for a moment.
Step 3: Square the differences from Step 1.
Step 4: Add up all of the squared differences from Step 3.
Step 5: Use the following formula to calculate the t-score:
ΣD: Sum of the differences (Sum of X-Y from Step 2)
ΣD2: Sum of the squared differences (from Step 4)
(ΣD)2: Sum of the differences (from Step 2), squared.
Step 6: Subtract 1 from the sample size to get the degrees of freedom. We have 11 items, so 11-1 = 10.
Step 8: Compare your t-table value from Step 7 (2.228) to your calculated t-value (-2.74). The calculated t-value is greater than the table value at an alpha level of .05. The p-value is less than the alpha level: p <.05. We can reject the null hypothesis that there is no difference between means.
You are learn about when to use the t-test and how to calculate. Also, learn what is means by t-test and uses of t-test.