Stat 2000: Tips for Assignment 5

Published: Mon, 11/17/14

Final Exam Prep Seminar Scheduled
The Final Exam Seminar will be Saturday, December 6 from 9:00 am to 6:00 pm, and will be held on the UM campus (room 100 St. Paul's College).
Did you read my tips on how to study and learn Stat 2000?  If not, here is a link to those important suggestions:
Did you read my Calculator Tips?  If not, here is a link to those important suggestions:
Did you see my tips for Assignment 1? Click here.
Did you see my tips for Assignment 2? Click here.
Did you see my tips for Assignment 3? Click here.
Did you see my tips for Assignment 4? Click here.
Tips for Assignment 5
Study the Chi-Square Goodness of Fit part of Lesson 9: Chi-Square Tests (in other words the rest of Lesson 9).  You also will need to study Lesson 10: Review of Linear Regression and Lesson 11: Inferences for Linear Regression (up to the end of question 3, you do not need to study the Multiple Linear Regression section at this time). 

Note that they appear to have omitted Multiple Linear Regression and Lesson 12: Nonparametric Tests (The Sign Test) this term. None of this appears on the current assignment, and they have omitted these topics every term lately.  DO NOT STUDY THESE SECTIONS.
Remember my advice in the tips above.  Don't start working on the assignment too soon.  Study and learn the lesson first, and use the assignment to test your knowledge.  Of course, always seek out assistance from my book, your course notes, etc. if you ever hit a question you don't understand, but try not to be learning things as you do an assignment.  Learn first, then put your learning to the test.

Exception: Always do any JMP stuff open-book.  Have my tips in front of you, and let me guide you step-by-step through any JMP stuff.  JMP is just "busy" work.  The sooner you get it done and can move on to productive things like understanding the concepts and interpreting the JMP outputs, the better off you will be.

Don't have my book?  You can download a free sample of my book and audio lectures containing Lesson 3:

A Warning about StatsPortal

Make sure that you are using Firefox for your browser.  Don't even use Internet Explorer.  It actually also has some glitches in the HTML editor boxes.

Do note that every time you exit a question in StatsPortal, the next time you return to it, the data may very well change.  Do not press the "back-up" button on your browser in a question.  That, too, will change the data.  When you are prepared to actually do a question, open the link, keep it open, and do not close it until you have submitted your answers.  Be sure to press "Save Answers" once you have done any calculations and entered any information to ensure the data does not change and force you to start over again.

After you submit the answer to a question, if you have been marked wrong on any parts, be sure that you write down the correct answers before you exit the screen (or grab a screen shot).  To try a second attempt at the question do not click the link to the question again, that will change the data and you will have to start all over again.  Also, DO NOT click "try again" or make a "second attempt."  That will also reset the data.

Instead, exit back to the home screen where they show the links for all the different questions on the assignment.  Where it shows the tries for a question on the right side of your screen, you should see the "1" grayed out, showing that you have had 1 attempt.  Click the number "2" to get your second attempt with the same data.  That way you can enter the answers you already know are correct and focus on correcting your mistakes.

You should also have already downloaded the JMP statistical software which was provided with either one of the course options for StatsPortal as mentioned in your course outline.

Make sure you have gone through Assignment 0 completely to learn how to use the interface.  I also suggest you print out a copy of question 8 in Assignment 0 (Long Answer Questions - Part 3) so that you have the steps for saving and uploading files into the HTML editor in front of you.

Question 1: Goodness of Fit
This is not unlike my question 5 in Lesson 9.  Make sure you follow their instructions for rounding.  They make their goodness-of-fit table horizontally, while I prefer to make mine vertically. 

When entering the bounds for the P-value, be sure to put the lower bound in the first box, then the upper bound in the second box.  Make sure you do that for all the questions in this assignment.

Similar to my Lesson 9, question 8.  They also then talk about estimating the parameter later in the problem which is like my Lesson 9, question 9.

Similar to my Lesson 9, question 11.  You should also look at my question 10 for additional practice.  Since the last cell represents when the count is 5 or more, make sure that the probability for that cell is such to make the total of all the probabilities add up to 1.  Make sure you are following their instructions for rounding of decimals carefully!

This is a runthrough of Linear Regression.  Be sure to study Lessons 10 and 11 in my book before attempting this and the rest of the questions in this assignment.  You should especially work through question 1 in Lesson 10 and questions 1 and 3 in Lesson 11.

Note that they give you SSE, the sum of the squared residuals, so you are able to compute the variance of the residuals (MSE = SSE/DFE).  MSE is your estimate for σ, as requested in part (e).  That is what I call Se, the standard deviation of the residuals, the estimate for σε, the standard deviation of the population of residuals.

Never forget , in a regression context, if they start talking about σ or s, they are referring to the standard deviation of the residuals for the population or sample, respectively.  To add to the confusion, they called s, σ-hat in this part.  They also use that symbol in question 6 below.

To do Linear Regression in JMP:
Open a "New Data Table".  Enter all the data for x in Column 1 and all the data for y in Column 2.  Be sure to name the columns appropriately.  Here, Column 1, x, will be Study Time and Column 2, y, will be Score.  Select "Analyze, Fit Y By X".  Highlight "Study Time" and click "X, Factor".  Highlight "Score" and click "Y, Response".  Click OK.

You should now be looking at a scatterplot.  Click the red triangle and select Density Ellipse and select 0.99 (it doesn't matter; you don't want this at all, but this gives you a summary of the means, standard deviations, and the correlation coefficient, r).  Click the red triangle that appears below the scatterplot which says Bivariate Normal Ellipse and deselect "Line of Fit" to make the ellipse disappear from your scatterplot.  You will also note that there is a title bar called Correlation below the scatterplot now.  Click the blue triangle to open it up and confirm the means and standard deviations match those you were given.  If not, perhaps you were mixed up which one was x and which one was y?

Click the red triangle and select "Fit Line" to get the least-squares regression line.  You now have all the outputs you need. 

Be sure to read in Lesson 11 the connection between the t test statistic for the slope and the t test statistic for the correlation.  And also the connection between t for the slope and F for the slope.  Although they want you to do a lot of this question by hand (and you certainly should since that will also happen on the exam), do note that JMP does do a lot of this stuff for you and you can use it to check your answers before you submit them.

This is similar to my Lesson 11, question 2.

I show you how to fill in an Anova table like this in Lesson 11, question 3.  Otherwise, similar to the previous couple of questions.

The correct answer is Yes, please!