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:

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

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.

This is a good overview of the concepts I teach in Lesson 1.  Especially look at my questions 6, 7 and 8.  Use the Inverse-Square Relationship I introduce in question 8 to answer parts (c) and (d). 

Careful, in part (c), they say they want to divide the margin of error by some amount.  There is no need to invert that value then before you square it.  For example, if they want to divide the margin of error by 5, that would mean you have to multiply the sample size by 25, the square of 5.

In part (d), where they don't give you the multiplier, take the old margin of error given in (a), and divide it by the new margin of error in (d) to get the appropriate factor.  Now merely square that factor.  Take that result and multiply it by the sample size found in (a) to get the answer you desire.  Do not use the sample size formula to answer this question.  It is too accurate.  They want you to use the inverse-square relationship.

Note that, in part (e), you should just use the sample size formula.

Just like question 2 above.  BE CAREFUL!  Make sure you are using the correct value for z*.  Is this test upper-tailed, lower-tailed, or two-tailed?  What does that mean about z*?

Yet more of the same.  To do part (c) more easily, read my part of Lesson 3 talking about "The Relationship between the Alternative Mean and the Power of a Test."

This is just a matter of typing your explanations into the box provided.  Make sure you click the HTML Editor link below the textbox before you type anything in.  This is like what I discuss at the start of Lesson 3 where the Type I error is "saying someone does not have cancer when they actually do."  Note that they also want you to describe the consequences of each error.  In my example, the consequences of a Type I error would be someone with cancer has gone undiagnosed, which may seriously affect their health, or perhaps even lead to a premature death.

This is a standard hypothesis test question where they have you do all five steps eventually, as taught in Lesson 2 of my book.  Make sure you are following their instructions for rounding off the decimals in each part.

This should be done both by hand (i.e. just using your calculator) and with JMP.

Click the HTML Editor link below the textbox before you start typing any answers in.  To type in the formula you are using and to show your numbers subbed into the formula click the button in the textbox that looks like the Sigma Summation symbol.  Then click the various buttons to make your fractions and enter the symbols.  Note, on my computer at least, when I click this Sigma button, the pop-up screen to enter the math equation gets hidden behind my webpage, so I have to minimize the StatsPortal screen in order to see the equation editor window.

Part (a) is fundamental.  See my discussion in Lesson 1 on why Inferences for the Mean are robust.

Part (b) is using an unusual level of confidence.  See my question 10 in Lesson 1 for an example.  Note that they want you to explain how you get z*.

Part (c) is standard.  I show you how to interpret a confidence interval in Lesson 1.

Note that you already know the z* critical value for part (d).  You used it in part (b).  You can use the Equation Editor as I mentioned above to write the formula work you are doing.

Parts (e) and (f) are standard P-value stuff.  I show you how to interpret a P-value in Lesson 2, question 6.

Part (g):  First, enter the data into JMP manually: Click the "New Data Table" icon on the toolbar at top left in the JMP home screen.  You are automatically taken to an empty spreadsheet with one column. Double-click "Column 1" and change its name to "Waiting Time", or right-click "Column 1" and select "Column Info" and type in the name "Waiting Time" and click OK.

Now just type in the various Waiting Time values in the cells using your "Tab" or down arrow button to move to each proceeding cell.  You can also hit "Enter" after each piece of data to enter it and move to the next cell.

Once you have entered all the data down your columns, you are ready to test the hypothesis and make your confidence interval.  In the toolbar at the top, select Analyze then select Distribution.  In the "Select Columns" part of the pop-up window, click the column you want to analyze ("Waiting Time" in this case) to highlight it, and click the Y, Columns button.  You should see the "Waiting Time" column 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 a histogram should appear.  Your histogram appears sideways.

To get JMP to make confidence intervals and test hypotheses for the mean:
To get a confidence interval, click the red triangle next to variable "Waiting Time" directly above the histogram to get a drop-down list and select "Confidence Interval".  In the pop-up window that appears, select "Other" (even if the level of confidence you desire is in the list) and type in the level of confidence you want (in decimal form, so 97%, for example, is 0.97).  Make sure "Two-sided" is selected.  You are given a value for sigma, the population standard deviation, so click the "Use known Sigma" checkbox.  Click OK.  You will get another pop-up window where you can type in your known value for sigma.  A Confidence Intervals table will appear in your output screen at the bottom.  Your lower and upper limits are shown under "Lower CI" and "Upper CI" in the Mean row.  These answers should agree with your computed answers in part (b) above.

To test a hypothesis, click that same red triangle you used to make a confidence interval and select "Test Mean".  Type in the value the null hypothesis believes the mean to be and type in the known value of sigma in the box that says "Enter the True Standard Deviation to do a z-test ...".  Click OK.  A "Test Mean =  Value" table appears in your output where, among other things, JMP gives you the test statistic and three probability values.  Those three probabilities are the P-value for the three possible alternative hypotheses.  JMP will use a z statistic since you gave it a sigma value.  It is up to you to know what the correct alternative hypothesis is, and so whether the test is two-tailed, upper-tailed, or lower-tailed.

• Prob > 'z' is the two-tailed P-value.
• Prob > z is the upper-tailed P-value.
• Prob < z is the lower-tailed P-value.

JMP's answer for the P-value should agree with what you calculated yourself in part (e).

Don't forget to answer part (h) in the text box!  I discuss this concept in Lesson 2, question 13(d) of my book.