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Assignment 3: One- and Two-TailedTests You are doing a study examining theeffect

ID: 2917995 • Letter: A

Question

Assignment 3: One- and Two-TailedTests

You are doing a study examining theeffects of studying method on academic achievement. All thestudents in your study take a course on genetics that lasts for 10days. One group of students studies 20 minutes a day for 10 days.The second group studies once at the end of the course but for 200minutes.

What is a one-tailed test? What is a two-tailed test? Explain atleast three differences between one- and two-tailed tests.

State a hypothesis related to this study that would causeyou to conduct a one-tailed test.

State a hypothesis related to this study that would causeyou to conduct a two-tailed test.

Write a one- to two-sentence explanation in aMicrosoft Word document

Explanation / Answer

A) 20 minutes a day for 10 days.

B) 2 00 minutes at once


What is a one-tailed test? What is a two-tailed test?

Atwo-tailed test plans (before the data is analyzed) to rejectthe null hypothesis if the test statistic is smaller but will alsoreject if greater than a specified value, for example below z=-1.96OR above z=+1.96. A one tail test rejects only if the teststatistic is in one direction, EITHER below -1.96 OR above +1.96.(The exact number is not important, just there for an example,could be 2.33 or some other value)

If you had a reason to expect that the students would performbetter on the test in group B, you do a one-tailed test instead.The critical z-value fora probability would be only in the upper tail. Your computed teststatistic of z and if itPOSITIVE and exceeds the critical value and falls in theregion of rejection, you reject the null hypothesis and saythat your Ho that the class was better with 200 minutes at once issupported. SO 1) A one tail has a predetermined idea about thedirection of the result, 2) only one area of rejection, 3) is morestringent for rejection criteria.


State a hypothesis related to this study that would cause youto conduct a one-tailed test.

Students do better if they study regularly for shortperiods.


State a hypothesis related to this study that would cause youto conduct a two-tailed test.

Students scores vary depending on if they regularly study forshort periods vs all at once.