How to Decide if a Hypothesis Test is a Left-Tailed Test or a Right-Tailed Test.
In a hypothesis test, you have to decide if a claim is true or not. The first step is to decide if you have a one-tailed test or a two-tailed test (How to decide if a hypothesis test is a one-tailed test or a two-tailed test) , then you need to decide if it’s a left-tailed test or a right-tailed test in order to figure out the z-score. This takes one step!
Sample hypothesis #1: drop out rate Sample hypothesis #2: drop out rate >75%
Step 1: Draw a normal distribution curve. Assume the area under the curve equals 100%, then shade in the related area.
This picture represent the phrase “less than 25%”. You can see that it would be a left-tailed test.
The yellow area could illustrate the area greater than 75%. From this diagram you can clearly see that it is a right-tailed test (because the shaded area is on the right.