| Grant's Updates for Stat 1000 |
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Hi ,
You are receing this e-mail because you indicated when you signed up for Grant's Updates that you are taking Stat 1000 this term. If in fact, you are not taking Stat 1000, please reply to this e-mail and let me know, and I will fix that.
Throughout the term I will send you all sorts of tips to help you study and learn the course. You probably already have done so, but, if not, I strongly recommend you purchase my Basic Stats 1 Study Book. You will find it a great resource to learn the course. I pride myself in explaining things in clear, everyday language. I also provided numerous examples of all the key concepts with step-by-step solutions. You can order my book at UMSU Digital Copy Centre at University Centre at UM campus. They make the book to order so please allow one business day. The book is split into two volumes and each volume costs $45 + tax.
If you ever want to look back over a previous tip I have sent, do note that all my tips can be found in my archive. Click this link to go straight to my archive:
Never forget, I am just a phone call or an e-mail away if you ever have any questions,
Grant |
| Tips for Assignment 3 of 12 |
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These tips are for those of you who are doing the Web Assign online assignments. Some of you are doing old-fashioned paper assignments. I think you should find these tips still useful, though. If there is a specific issue you are still having trouble with, do not hesitate to contact me. Do note that there are a total of 12 assignments in the Web Assign system. If your particular prof is issuing only 6 assignments for the term, you will probably also want to take a look at the tips I send for Assignment 4 of 12 as well.
Those of you who are doing this course by distance/online are doing the course in a different order than those of you who are taking the lecture version of the course. If you are taking the course by distance/online study Lesson 2 in my book to prepare for Assignment 3. Those of you who are taking the lecture course will omit Lesson 2 in my book for now. Lesson 2 will not be covered until after your first midterm exam. Those of you who are taking the lecture version should study Lesson 3 to prepare for Assignment 3.
Note, in question 3, a "cumulative proportion" is a left area on the bell curve. Cumulative proportion is P(Z < z).
For those of you in Distance Ed, do not use CrunchIt! in the problems that tell you to. You are using JMP 8 in this course. CrunchIt! is no longer able to do some of the things they ask, so you may as well not bother using it at all.
For the JMP 8 part of the assignment, here are some tips:
Open a "New Data Table" in JMP. To copy and paste the data into JMP, in the toolbar at top select "Edit" then "Paste with Column Names". Double-click the "gpa" column heading and make sure the Data Type is Numeric and the Modeling Type is Continuous, using the drop-down menus to fix that if necessary. Double-click the "sex" column heading and make sure the Data Type is Character and the Modeling Type is Nominal, using the drop-down menus to fix that if necessary. Click OK.
To get side-by-side boxplots: In the toolbar at the top, select Analyze then select Fit Y By X. In the pop-up menu, highlight the gpa column and click the Y, Response button. Highlight the sex column and click the X, Factor button. Click OK. You will then see a graph with a vertical array of dots for the males (1) and the females (2). Click the red triangle next to "Oneway Analysis ..." and select "Display Options". You will then be able to select "Box Plots" in the Display Options sub-menu.
To get normal quantile plots: Click the red triangle and select the option Normal Quantile Plot. Choose "Plot Actual by Quantile" in the sub-menu. This portrays the normal quantile plot for the males and females on the same graph, but colour codes which plot is for which sex.
But, they want you to make a normal quantile plot for the males and a separate plot for the females, you have to do it this way:
In the toolbar at the top, select "Analyze" , then "Distribution". In the pop-up menu, highlight "gpa" and click "Y, Column". Highlight "sex" and click "By". Click OK. You now see separate histograms for the males and for the females. Click the red triangle next to "gpa" for both the males and for the females, and select "Normal Quantile Plot" to get a separate normal quantile plot for the males and females.
A normal quantile plot checks to see if a sample's distribution appears to be normal. If the data follows a normal distribution, the normal quantile plot will look like a rising diagonal line. If the plot looks curved rather than linear, there is evidence the data is not normal. However, none of that seems to matter in your question, all they ask is which students are clear outliers, which, personally, I think is much easier to see from your side-by-side boxplots than from your normal quantile plots.
For Question 1, follow my example in Lesson 3, question 1, part (c) to see how to compute r by hand. Note you are certainly allowed to use the Linear Regression Stat Mode on your calculator to tell you the means and standard deviations of both x and y. Note, only those of you who have my blue or green study book have an example that follows exactly the headings given in this question. Even though they tell you to do everything to three decimal places, don't do that. Record every single decimal place your calculator gives you for each calculation, or else your answers won't be accurate enough. I suggest you do everything on paper first, then you can type in the results, rounding all of your numbers off to 3 decimal places at that time (even though you actually did the calculations using all the decimal places).
Question 2 is an algebra problem. They have given you three out of the four values in the least-squares regression equation, solve the missing one.
Here is how to do the computer part of Question 5 (use JMP):
If you are using JMP, first paste the data into a New Data Table the usual way (see my previous homework tips if you are not sure how to paste the data). Select Analyze, then Fit Y By X. Highlight the column you have determined should be X, and click the X, Factor button. Highlight the column you have determined should be Y and click the Y, Response button. Click OK.
You should now see a scatterplot. Click the red triangle above the scatterplot and select Fit Line and JMP will draw in the least-squares regression line. Note, it shows you the regression equation directly below the scatterplot. JMP also shows you the value of r-squared (the coefficient of determination), rather than r, the correlation coefficient.
Note, you must save your document as a PDF file to upload it into Web Assign (no other format will be accepted). If you don't know how to do this for the software you are using try the help files or Google "save as pdf file" for some helpful steps or programs that enable you to save documents that way for free. MS Word 2007 is capable of saving as pdf. If you are using a different program and do not have a "save as pdf" option, Google "pdf995 download" for a free program that can be used to save documents in a pdf format. Note also that if you have had to download a program to create pdf files, most of these programs create a "pdf printer" in your printers list. In order to save the file as a pdf file, you would actually behave as though you were printing the file, but when you choose print, select your pdf printer and it will actually creatge a pdf file.
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