Learn by Doing

This activity gives you practice explaining the different parts of the StatCrunch print-out for a hypothesis test for a population mean. You will review the meaning of standard error, T-scores and the P-value.

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Here are the directions, grading rubric, and definition of high-quality feedback for the Learn by Doing discussion board exercises.

A list of StatCrunch directions is provided at the bottom of this page.

Prompt

1. In a previous lab we tested the following hypotheses,
   $H$
   

   
   0
   :

   $μ$
   

   
   =
   
   
   4.73
   and

   $H$
   

   
   a
   :

   $μ$
   

   
   <
   
   
   4.73
   (where

   $μ$
   

   is the mean number of alcoholic drinks consumed by students at a liberal arts college).

   In a random sample of 75 students, the mean was 3.93 alcoholic drinks consumed in a week. Here is the StatCrunch output from the hypothesis test.
   

   $\mathrm{<br>\; μ<br>}$
   

   : Mean of variable
   

   ${}_{}$
   
   H
   
   
   

   
   0
   :

   $μ$
   

   
   =
   
   
   4.73
   
   

   $H$
   

   
   A
   :

   $μ$
   

   
   ≠
   
   
   4.73
   

   Hypothesis test results

   Variable	Sample Mean	Std. Err.	DF	T-Stat	P-value
   number of drinks per week	3.9333333	0.43592434	74	-1.8275343	0.0717

   Using this context and the StatCrunch output, explain the meaning of each of the following.

   1. Std. Err (standard error)
   2. T-stat (T-score)
   3. P-value
2. In a previous matched pairs lab we tested the following hypotheses, where
   $μ$
   

   is the mean of the differences in corn yield for a plot of land (regular seed minus kiln-dried): H0: µ = 0 and Ha: µ < 0. In a random sample of 11 seeds of each type, the mean of the differences in the sample was -33.7. Here is a StatCrunch print-out of the hypothesis test.

   Paired T hypothesis test:
   

   $μ$
   

   
   D
   
   
   =
   
   
   
   μ
   
   
   1
   
   
   
   −
   
   
   
   μ
   
   
   2
   
   : Mean of the difference between Regular seed and Kiln-dried seed
   

   $H$
   

   
   0
   :

   $μ$
   

   
   D
   
   
   =
   
   
   0
   
   

   $H$
   

   
   A
   :

   $μ$
   

   
   D
   
   
   <
   
   
   0
   

   Hypothesis test results

   Difference	Mean	Std. Err.	DF	T-Stat	P-value
   Regular seed – Kiln-dried seed	-33.727273	19.951346	10	-1.6904761	0.0609

   Differences stored in column, Differences.

   Using this context and the StatCrunch output, explain the meaning of each of the following.

   1. Std. Err (standard error)
   2. T-stat (T-score)
   3. P-value.

Grading

To view the grading rubric for this discussion board, click on menu icon (three vertical dots) and then select show rubric. Please note, if viewing the course via the Canvas mobile app the rubric does not appear on this page.

Tips for Success

• • • Did you make a mistake in your initial post? No problem! Just be sure to reply to yourself and note any corrections that need to be made.
    • You are required to reply to two of your peers in this discussion; don’t forget to complete this requirement of the activity or you will lose points. Provide high-quality feedback to your peers.