Did you read my tips on how to study and learn Stat 1000?  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:

Don't have my book?  You can download a free sample of my book and audio lectures containing Lesson 1:

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.  Instead, 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.

This is a standard question about classifying variables, similar to my question 1 in Lesson 1.

Remember, if you find the total of the second column (the frequency or count column) in a frequency table, that will tell you n, the sample size.

This deals with some aspects of quantitative distributions.  Note that part (a) wants a decimal, not a percent.  For example, if you figured out that the proportion is 20/30 are in this interval, 20 divide by 30 is 0.6667, not 66.6667%. 

Part (b):  Remember that a frequency table is a precursor to a histogram.  Visualize the histogram (don't actually make a histogram, just picture it) to help answer the questions.  Remember, quartiles break the data up into 25% sections.  You cannot actually compute the median, mean or quartiles because you do not have the actual data.  You don't need to.  The shape of the distribution is enough to know if the mean is larger, smaller or the same as the median. 

Part (d):  You do know the sample size, n, (the total count in the Frequency column), so you can use the steps I teach in Lesson 1 to find the location of any quartile .  Then just make a running total of the counts in the intervals.  How much data is in the first interval? (The count or frequency as given in the second column.)  Now add the count in the second interval (for example if there are 3 scores in the first interval, and 7 scores in the second interval, that means there are 3+7=10 scores in total in the first two intervals.  Those must be the 10 lowest scores in the data set.  Continue adding the frequencies in each interval until you reach or exceed the count you are looking for that marks the location of the first, second or third quartile as desired.

Make sure you compute the five-number summary by hand, as I demonstrate in Lesson 1, question 4.  Of course, as I also teach in that same question, you will use the 1.5 IQR rule to establish the outliers.

Do not use JMP for the back-to-back stemplot in part (a).  Take a look at my Lesson 1, question 7 for an example of a back-to-back stemplot.  I suggest you make the stemplot on paper first, then transfer it to the box.  Make sure you click "HTML Editor" below the box BEFORE you type anything in.

Use the vertical line on your computer keyboard to separate the stem from the leaves ("SHIFT \" will give you " | ").  Don't worry if your columns don't end up perfectly lined up, just do the best you can.  Be sure to label the first line in your stemplot "Leaf | Stem | Leaf", then enter all the stems and leaves row-by-row underneath.  It will be pretty difficult to make the data line up nicely when you type the stemplot into the HTML editor, but I don't think you should waste much time trying to make it look pretty.

If you prefer, you could make the stemplot in Word by inserting a table with 3 columns to represent the Leaf, Stem, and Leaf columns, then copy the table you made and insert it into the HTML editor box, by selecting Edit on the HTML editor toolbar and clicking Paste from Word.

To make the histograms in part (b):
First, enter the data into JMP manually: Click the "New Data Table" icon on the toolbar at top left in the JMP home screen (or select "File" in the toolbar, then New, then Data Table).  You are automatically taken to an empty spreadsheet with one column. Double-click "Column 1" and change its name to "Male Tip %", or right-click "Column 1" and select "Column Info" and type in the name "Male Tip %" and click OK.  Then double-click the region to the right of the first column name to automatically create a second column.  Or, select "Cols" in the toolbar at the top of the screen, and click New Column to create a second column.  Rename that second column "Female Tip %" using the same method as you did for the first column above. 

Now enter the data you have been given into these two columns.  Note you can use your arrow buttons or TAB button to move from one cell to the next as you enter your data.

Once you have entered all the data down your columns, you are ready to make your histograms.  In the toolbar at the top, select Analyze then select Distribution.  In the "Select Columns" part of the pop-up window, hold down the CTRL key on your keyboard and click both column names you want the histograms for ("Male Tip %" and "Female Tip %" in this case) to highlight them, and click the Y, Columns button.  You should see both column names appear in the section to the right of the "Y, Columns" button.  Click OK.

It now opens yet another pop-up window called "Distributions" where your histograms should appear.  Your histograms are sideways. If you want to see them the typical way, (but they didn't ask you to do this, so don't bother), click the red triangle next to "Male Tip %" above the histogram and select Histogram Options from the drop-down menu.  Deselect "Vertical" and it will turn it the proper way (horizontal layout).  Repeat this for the red triangle next to "Female Tip %".

If you want to hide all the other parts of the output (but they said you don't have to), click that same red triangle again and deselect "Outlier Box Plot" and anything else that has a check mark next to it.  Click the red triangle again, select "Display Options" and deselect "Quantiles" and "Summary Statistics" to make those parts disappear.  Alternatively, you can make the Quantiles and Summary Statistics disappear if you simply click the gray triangles (to the left of the red triangles) next to their title bars.  Click the gray triangles again to make them reappear.

You are now ready to insert your histograms into the HTML editor box:

• If you are using Windows:
• Press "Alt" on your keyboard or click the thin blue line that is near the top of the window to get the toolbar icons to appear.  Select "File" then "Save As" to get a pop-up window.  Type in whatever name you want the file to have in the "File name" section. Click the "Browse Folders" arrow and select which folder you want to save the file in (I suggest you select "Desktop" so that the file will just appear right on your desktop home screen).  Finally, click the drop down arrow in the "Save as type" section and select "JPEG File".  Click "Save".  You should now have your file ready to upload into the assignment.
• To upload your file into the text box they provide: Click "HTML editor" below the text box (if you have not already done so) to make a toolbar appear in the text box.  Click the toolbar option called "Link" and select "Image."  In the pop-up window that appears, click the button called "Find/Upload File" (it is at the bottom of the pop-up window, you may have to enlarge the box or scroll down to see it).  Click the "Browse" button and find the histogram file you just saved.  Either double-click that file or select it and click "Open" and you should see the path to that file appear in the Browse box.  Click "Upload File" and its name should appear in the "Uploaded Files" pop-up window.  Select the file in the list of "Uploaded Files" to highlight it and click OK and you should see the file appear in the text box. 

• If you are using Apple/Mac:
• You will need to take a screen shot of your output in order to upload it.  To take a screen shot hold down Command+Shift+4 and drag the cross-hairs over the image to capture it.  The image will save a .png file to your desktop by default.
• To upload your file into the text box they provide: Click "HTML editor" below the text box (if you have not already done so) to make a toolbar appear in the text box.  Click the toolbar option called "Link" and select "Image."  In the pop-up window that appears, click the button called "Find/Upload File" (it is at the bottom of the pop-up window, you may have to enlarge the box or scroll down to see it).  Click the "Browse" button and find the histogram file you just saved.  Either double-click that file or select it and click "Open" and you should see the path to that file appear in the Browse box.  Click "Upload File" and its name should appear in the "Uploaded Files" pop-up window.  Select the file in the list of "Uploaded Files" to highlight it and click OK and you should see the file appear in the text box.

To make the side-by-side boxplots in part (c):

Open a "New Data Table" in JMP.  DO NOT USE THE DATA TABLE YOU MADE TO MAKE THE HISTOGRAMS IN PART (B).

You will make two columns, but not the way you might think. DO NOT put the Male Tip %  in one column and the Femal Tip % in another!

Double-click Column 1 (or right-click and select Column Info) and name it "Tip %".  Type all 22 scores from the Female Tip % column first (note that they want you to put the Female Tip % scores first even though that is the second column of data given in the question.  Then enter the 23 scores from the Male Tip % data, giving you a total of 45 rows in the first column. Double-click the region to the right of Column 1 at the top to create Column 2 and name that column "Gender."  Type "Female" in the first 22 rows of that column (better yet, type it once, copy and paste it into the next 21 rows; that way you ensure it is typed exactly the same in all 22 rows as is necessary).  Then type (or copy and paste) "Male" in the remaining rows of column 2.

To make the side-by-side boxplots:
Select "Analyze" then "Fit Y By X".  Highlight "Tip %" and click "Y, Response".  Highlight "Gender" and click "X, Factor".  Click OK.  This should open a pop-up window with a bunch of dots arranged vertically in two columns on a graph for "Female" and  "Male".  If  that does not happen, return to the data table and double-click each column (or right-click and select column info).  The Tip % column better have Data Type as "numeric" and Modeling Type as "continuous."  Change those settings if not.  The Gender column better have Data Type as "character" and Modeling Type as "nominal."  Change those settings if not.

Now click the red triangle next to "Oneway Analysis ..." and select "Quantiles."  Your side-by-side box plots should appear on the graph as well as a Quantiles output below that shows you the five-number summary among other things.  Click the red triangle again and select "Display Options" (down near the bottom of the menu), then deselect "Grand Mean" to get rid of the horizontal line in the graph showing the mean of all the scores.  Click the red triangle once more, select Display Options again, and deselect "Points" to remove the data points on the graph.

You are now ready to insert your boxplots into the HTML editor box:

• If you are using Windows:
• Press "Alt" on your keyboard or click the thin blue line that is near the top of the window to get the toolbar icons to appear.  Select "File" then "Save As" to get a pop-up window.  Type in whatever name you want the file to have in the "File name" section. Click the "Browse Folders" arrow and select which folder you want to save the file in (I suggest you select "Desktop" so that the file will just appear right on your desktop home screen).  Finally, click the drop down arrow in the "Save as type" section and select "JPEG File".  Click "Save".  You should now have your file ready to upload into the assignment.
• To upload your file into the text box they provide: Click "HTML editor" below the text box (if you have not already done so) to make a toolbar appear in the text box.  Click the toolbar option called "Link" and select "Image."  In the pop-up window that appears, click the button called "Find/Upload File" (it is at the bottom of the pop-up window, you may have to enlarge the box or scroll down to see it).  Click the "Browse" button and find the boxplots file you just saved.  Either double-click that file or select it and click "Open" and you should see the path to that file appear in the Browse box.  Click "Upload File" and its name should appear in the "Uploaded Files" pop-up window.  Select the file in the list of "Uploaded Files" to highlight it and click OK and you should see the file appear in the text box. 

• If you are using Apple/Mac:
• You will need to take a screen shot of your output in order to upload it.  To take a screen shot hold down Command+Shift+4 and drag the cross-hairs over the image to capture it.  The image will save a .png file to your desktop by default.
• To upload your file into the text box they provide: Click "HTML editor" below the text box (if you have not already done so) to make a toolbar appear in the text box.  Click the toolbar option called "Link" and select "Image."  In the pop-up window that appears, click the button called "Find/Upload File" (it is at the bottom of the pop-up window, you may have to enlarge the box or scroll down to see it).  Click the "Browse" button and find the boxplots file you just saved.  Either double-click that file or select it and click "Open" and you should see the path to that file appear in the Browse box.  Click "Upload File" and its name should appear in the "Uploaded Files" pop-up window.  Select the file in the list of "Uploaded Files" to highlight it and click OK and you should see the file appear in the text box.

Now type your answer to part (d) into the HTML editor.  Do not compute any additional measures of centre and spread, you have the boxplots to estimate these things.  Do Male Tip % and Female Tip % have the same shape or different? Same Centre? Same Spread? If not, which has a higher Centre, a larger Spread?

Look at my Lesson 1, questions 19 and 20 for examples of how to establish the value of a mean if a data set is changed.  It is all about establishing what the total of the scores used to be, and then how the new data being added or removed changes that total.

To make the Time Series:
First, you will have to open a new data table in JMP.  Double-click the region to the right of  Column 1 to make a second column, Column 2.  Rename Column 1 "Year" and Column 2 "Estimated Consumption." Type in the data you have been given.

You are now ready to make the time series.  Select Analyze in the toolbar, then select Modeling in the drop-down list and finally select time series.  Select the variable you are tracking "Estimated Consumption" and click "Y, Time Series".  Select the time variable, "Year" and click "X, Time ID."  Click OK.  In that other pop-up menu asking about time lags or autocorrelations or whatever, they want you to enter "2" (but really it is irrelevant) and click OK and move on. 

You should now be looking at your Time Series with "Year" on the horizontal axis and "Estimated Consumption" on the vertical axis.  Click the red triangle next to "Time Series Estimate Consumption" and deselect "Autocorrelation" and "Partial Autocorrelation" to remove those parts of the output.  Click the red triangle again, select "Graph" then deselect "Mean Line".  That removes the horizontal line in your time series showing the mean points score.

You are now ready to insert your time series into the HTML editor:

• If you are using Windows:
• Press "Alt" on your keyboard or click the thin blue line that is near the top of the window to get the toolbar icons to appear.  Select "File" then "Save As" to get a pop-up window.  Type in whatever name you want the file to have in the "File name" section. Click the "Browse Folders" arrow and select which folder you want to save the file in (I suggest you select "Desktop" so that the file will just appear right on your desktop home screen).  Finally, click the drop down arrow in the "Save as type" section and select "JPEG File".  Click "Save".  You should now have your file ready to upload into the assignment.
• To upload your file into the text box they provide: Click "HTML editor" below the text box (if you have not already done so) to make a toolbar appear in the text box.  Click the toolbar option called "Link" and select "Image."  In the pop-up window that appears, click the button called "Find/Upload File" (it is at the bottom of the pop-up window, you may have to enlarge the box or scroll down to see it).  Click the "Browse" button and find the time series file you just saved.  Either double-click that file or select it and click "Open" and you should see the path to that file appear in the Browse box.  Click "Upload File" and its name should appear in the "Uploaded Files" pop-up window.  Select the file in the list of "Uploaded Files" to highlight it and click OK and you should see the file appear in the text box. 

• If you are using Apple/Mac:
• You will need to take a screen shot of your output in order to upload it.  To take a screen shot hold down Command+Shift+4 and drag the cross-hairs over the image to capture it.  The image will save a .png file to your desktop by default.
• To upload your file into the text box they provide: Click "HTML editor" below the text box (if you have not already done so) to make a toolbar appear in the text box.  Click the toolbar option called "Link" and select "Image."  In the pop-up window that appears, click the button called "Find/Upload File" (it is at the bottom of the pop-up window, you may have to enlarge the box or scroll down to see it).  Click the "Browse" button and find the time series file you just saved.  Either double-click that file or select it and click "Open" and you should see the path to that file appear in the Browse box.  Click "Upload File" and its name should appear in the "Uploaded Files" pop-up window.  Select the file in the list of "Uploaded Files" to highlight it and click OK and you should see the file appear in the text box.

Don't forget to type your answer about the overall trend in the HTML editor box.  Take a look at my question 3 in Lesson 1 for an example of a time series and how to describe it.  Is there a trend?  Did the trend change at some point?  If so, when?  Is there perhaps a seasonal variation?  If so, what is that variation?  These are the kinds of questions you ask yourself when describing a time series.

This question should be done by hand (i.e. with your calculator, not with JMP).  Use the Stat Mode on your calculator to compute the Mean and Standard Deviation.  Check the Appendix at the back of my book to learn how to use the Stat Mode on your calculator.  Here is a link to a digital copy of that appendix:

Make sure you round the answers off to 2 decimal places before proceeding to answer the other parts of the question.

Part (b) is introducing a key concept about changing the units in data.  Be sure to read the "Effect of Changing Units on Centre and Spread" section of my book in Lesson 1 and see questions 17 and 18 for examples.  As they say, once you know the mean and standard deviation from part (a), you can convert them into the mean and standard deviation for part (b) using the conversion information they gave you at the start.  Here, you have to multiply the scores by a certain amount, then add on the incentive bonus to convert the amount spent to the loyalty points.

Rather than convert each piece of data, you can apply this recipe to the mean and standard deviation of the amount spent to get the mean and standard deviation of the loyalty points.  But do it properly! Remember, addition or subtraction has no effect on spread, only multiplication or division does.  While everything affects measures of centre.

For part (c), consider this:  Let's say you are taking a course, and your average mark so far is 65.  What will happen to your average if you score higher on the next test?  What if you score lower on the next test?  What would you have to get on the next test to have your average stay 65?

For part (d), having decided what that new score must be in part (c), how much does that score deviate from the mean? If that is a larger deviation than the standard deviation you computed earlier, you have increased the overall standard deviation; if it is the same amount of deviation as earlier, you have not changed the standard deviation at all; if it has a smaller deviation, you have decreased your overall standard deviation.

First, you need to know the scores attached to each letter grade.  An A+ is 4.5, A is 4, B+ is 3.5, B is 3, etc.

To compute your grade point average:
First, make a new column where you multiply each grade score by the number of credit hours.  For example, if you got a B+ in a 3 credit-hour course, you would multiply 3.5 by 3 to get 10.5 in this new column. Find the total of this new column and find the total number of credit hours.  Divide the total of the new column by the total number of credit hours to get the GPA.  Put another way, if you got a B+ in 3 credit-hour course, it is as though you scored 3.5 three separate times.  You could put your calculator in Stat Mode, and enter 3.5 in three separate times.  If you got an A in a 6 credit-hour course, you got 4.0 six times.  Enter 4.0 six separate times.  After you have entered all the data, your calculator will tell you the mean (your GPA).

An easy way to think of grade points is to consider the amount of credit hours as the frequency of that grade.  Gettting an A in a 3-credit hour course, is like getting an A 3 separate times.  Getting a C in a 6-credit hour course is like getting a C 6 separate times.  It is like finding the average of three A's and six C's.