statistic crunch homework

STATCRUNCH #2 Due on the day of the final exam. PRINT OUT and bring with you.

Name:________________________

A reminder that this assignment is YOUR OWN work. It is not a group project, although you may talk about the process to other students, you are not to share answers.

Part I - Hypothesis Testing

Open StatCrunch http://www.statcrunch.com/ use the same sign in as you do with MyStatLab.

Go to EXPLORE then DATA, to the left under “view options” in the BROWSE ALL box type Car_MPG_Data and click “search” You will find the data set with the following description:

Data on cab space (cu. ft.), horsepower, average MPG, top speed (mph), and weight (hundreds of pounds). Based on data provided by the U.S. Environmental Protection Agency. Reported in R.M. Heavenrich, J.D. Murrell, and K.H. Hellman, Light Duty Automotive Technology and Fuel Economy Trends Through 1991, U.S. Environmental Protection Agency, 1991 (EPA/AA/CTAB/91-02). Data set copied from http://lib.stat.cmu.edu/DASL/Datafiles/carmpgdat.html

Using this data, a dealership made the claim that small cars have an average MPG that is greater than 40. Defining small cars as those weighing 30 ( hundred pounds) or less. Use the data above to test the dealership’s claim. Use StatCrunch to find your p-value and then on paper NEATLY show all steps involved in your hypothesis test.

1) On StatCrunch under STATS you will find Z Stats ( Z-test), T Stats (T-test), Proportion Stats ( Prop-z Test). Determine which test you have to perform, then figure out if you have one sample or two samples (Here you have DATA so make sure you select data)

2) Once you decide which test you are performing, select the column for MPG since that’s what the claim is referring to. You also have to click BUILD to select what we consider small cars 30 ( hundred pounds) or less . Select WT then “add column” and the less than equal to symbol. Don’t forget to type in the 30 and click OKAY

Copy your output from Statcrunch and NEATLY show ALL steps involved in your hypothesis test HERE:

Must be labeled as “Step 1”, “Step 2”….etc.

Part II - Linear Regression

Getting your textbook data by going to StatCrunch directly:

Go to www.StatCrunch.com Sign in with your MyStatLab user ID and PW. You will have successfully logged in if you see this window ( with your name instead of my name…. of course)

Click on EXPLORE ( located on the top left) of your window. You are then given 4 options. Select “GROUPS”. Go to the left side of your screen, under View Options, there is a “browse all” box. Type in Triola then click on the group “Triola Elementary Statistics 11th Edition”. Click on 25 data sets to see all of the data sets (otherwise you will only see the top 5). Look for “Bears (wild bears anesthetized) and click on it.

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Here are the 9 variables in our data set:

· Age = is the age of the bear in months

· Month = the month the bear was measured (Jan – Dec)

· Sex = female = 2 and male = 1

· Headlen = head length in inches

· Headwth = head width in inches

· Neck = distance around neck in inches

· Length = length of body in inches (not including head)

· Chest = Distance around chest (in inches)

· Weight = weight of bear measured in pounds

· Constructing a Scatter Plot and finding Regression Line:

Go to STAT, select REGRESSION then SIMPLE LINEAR (to get the window below). Adjust your information so it matches the window below ( what you can see on this snapshot leave as default on your window) and click COMPUTE!

This will give you a simple linear regression for female bears and a separate simple linear regression for male bears. Use the arrows at the bottom to see all your results.

Answer the following questions:

( TYPE out your answers for full credit)

1) Female Bears:

correlation coefficient:

p-value:

Is there significant correlation to use a regression line? Show your work:

2) Male Bears:

correlation coefficient:

p-value:

Is there significant correlation to use a regression line? Show your work:

3) What does the correlation imply about the relationship between the length of a bear and the height of a bear? Answer with 1-3 complete sentences.

4) For female bears write down the regression line ( if there is a significant correlation to use a regression line) :

5) For male bears write down the regression line ( if there is a significant correlation to use a regression line) :

6) Paste two scatter plots here. One for female bears and one for male bears, each with it’s own regression line. Remember to click on OPTIONS located in the top left corner of your window and select “copy” from the drop down menu. Paste that graph on to this document ( in the space provided below). There are special instructions for pasting. Follow instructions given. On a word document you have to do a “’paste special” and select device independent bitmap.

a. Does the line seem to fit the data? Why? Answer with 1-3 complete sentences.

7) Using the data you obtained and using the result of your analysis, supply an answer for the following scenarios:

a. For female bear 45 inches tall , predict it’s weight:

b. For a male bear 55 inches tall, predict it’s weight.