Stat 2000: Tips for Web Assign HW 01
Published: Mon, 01/17/11
Hi ,
Join Grant's Tutoring on Facebook or follow Grant on Twitter.
Simply go to www.grantstutoring.com and click the Facebook and/or Twitter icons.
You are receing this email because you indicated when you signed up for Grant's Updates that you are taking Stat 2000 this term. If in fact, you do not want to receive tips for Stat 2000, please reply to this email and let me know.
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:
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 2 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 at least one business day. The book is split into two volumes and each volume costs $45 + tax.
Tips for Web Assign HW 01
When working with Web Assign, always enter the answer to one specific box and then click "Submit Answer" to confirm that is correct before you move on to another box. Do not enter several answers all at once in several boxes before you click "Submit Answer". You risk being marked wrong due to some typo or something.
For some strange reason, JMP 8 occasionally computes wrong answers even if you have copied and pasted your data correctly. I suggest that, if it is feasible, type the given data into your calculator (in Stat mode as shown in Appendix D of my book), and have your calculator compute the sample mean. Compare that answer with JMP's answer for the sample mean. If they are the same, everything is fine. If they are not the same, close JMP 8 and restart it, recopy and paste the data, and check again. Sometimes you have to do this 2 or 3 times before JMP finally works. If it is not feasible to use your calculator to compute the sample mean, have JMP do the question 2 or 3 times, being sure to restart JMP and recopy the data each time, and confirm that JMP gives you the same answer each time before risking entering the results into Web Assign.
If you are taking the course by distance/online (Section D01) click here to see your tips for HW 01.
Study Lessons 1 and 2 in my study book (if you have it) to learn the concepts involved in the first half of HW 01 (up to the end of question 5). You will also have to study Lesson 3 in my book, but leave that until I tell you to do that later in these tips. It is essential that you take the time to get a thorough understanding of Lessons 1 and 2 first. That will set you up for the whole course. The student who struggles in those concepts will never be able to progress. The student who feels comfortable with these lessons, will find that the rest of the course flows at a smooth and steady pace.
Note that this entire assignment uses z, not t since they always give you the population standard deviation, σ.
Question 1 is using the formulas for the standard deviation of the mean, confidence interval for a mean I teach in Lesson 1 of my book. Be sure to use your calculator in Stat mode to compute the sample mean (see Appendix D of my book).
Question 2 is using an unusual level of confidence. See my question 10 in Lesson 1 to understand how to deal with that. You will also need the formula for sample size determination I give in this lesson.
Question 3 is using the 5 steps to test a hypothesis I teach in Lesson 2. Note, since you are asked to compute a P-value, you can skip step 2.
Question 4:
When you are copying data into JMP 8, first open JMP and select "New Data Table". To make sure the column headings are pasted properly, select and copy the data, then be sure to select "Edit" in the JMP toolbar and select "Paste with column names". Then your data should paste properly. JMP has a nasty habit of messing up when this is done, though. If your column contains numbers (quantitative data), make sure you double-click each column heading and confirm that the Data Type is Numeric and the Modeling Type is Continuous (JMP may have changed the Data Type to Character and the Modeling Type to Nominal).
To get JMP to make confidence intervals for the mean:
Select Analyze, Distribution from the toolbar at top. Highlight the column you are interested in ("drp" in this case) and click the "Y, Columns" button. Click OK. You are now taken to a window showing a histogram and stuff. To get a confidence interval, click the red triangle next to your column variable 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 95% is 0.95). Make sure "Two-sided" is selected. If you are given a value for sigma , the population standard deviation, (and you are in this question) select 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.
To get JMP to test hypotheses for the mean:
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, if you have one (otherwise leave that value blank). 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 if you are given a sigma value to enter or a t statistic if sigma is unknown.
Prob > |z| or Prob > |t| is the two-tailed P-value.
Prob > z or Prob > t is the upper-tailed P-value.
Prob < z or Prob < t is the lower-tailed P-value.
To get rid of any outputs you don't want to copy and paste, click the red triangle and deselect the unwanted things.
To copy and paste the parts of a JMP printout you do want, select the icon on the JMP toolbar that looks like a fat white plus sign "+" (the Selection tool). You can then click various parts of the printout to select the sections you want. Copy and paste into Word or something like that.
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 that, if you are using a program like this, often it loads a "pdf printer" onto your computer. Then, to save your file as pdf, you actually select "print" as though you were going to print your file, then select your "pdf printer" rather than your physical printer in the print options. That will then save your file in pdf form.
Question 5:
Similar to questions above in the assignment.
At this point, study Lesson 3 in my book before you complete the assignment.
Questions 6 to 9 should go quite smoothly for a person who has studied Lesson 3 in my book.
To be able to understand questions 10 and 11, you will need to read my "errors in Hypothesis Testing Revisited" section in Lesson 6 of my study book (this is only in the 2010-2011 edition, blue cover). You may also need to skim through some of the earlier questions in Lesson 6 to get a grasp of how to compute Discrete Probabilities and Binomial Probabilities. I think mastery of these topics is not important at this time, you will get an opportunity to learn this lesson more thoroughly later on in this course.
Questions 12 and 13 are just more review of the concepts learned in Lessons 1, 2 and 3.
Study Lessons 1 and 2 in my study book (if you have it) to learn the concepts involved in HW 01. It is essential that you take the time to get a thorough understanding of Lessons 1 and 2 first. That will set you up for the whole course. The student who struggles in those concepts will never be able to progress. The student who feels comfortable with these lessons, will find that the rest of the course flows at a smooth and steady pace.
Note that this entire assignment uses z, not t since they always give you the population standard deviation, σ.
Ignore any references to JMP 6SE or Crunchit!. You are using JMP 8 in this course. The assignment is just an old assignment that they forgot to update. Use JMP 8 anytime they tell you to use computer stuff.
Question 5 part a is using the formulas for mean and standard deviation I teach at the start of Lesson 6 in my study book. Read the first few pages and try questions 1 and 2 to help you prepare for this assignment question. The rest of question 5 uses the properties for mean and variance I teach in Lesson 4 of my study book (this is only the 2010-2011 edition of my book, blue cover). Again, you need to only look at the first couple of questions I do in Lesson 4 to assist with this question. Leave thorough study of Lessons 4 and 6 until later on in this course.
Question 6 is using the formulas for confidence interval for a mean and sample size determination I teach in Lesson 1 of my book.
Question 7:
When you are copying data into JMP 8, first open JMP and select "New Data Table". To make sure the column headings are pasted properly, select and copy the data, then be sure to select "Edit" in the JMP toolbar and select "Paste with column names". Then your data should paste properly. JMP has a nasty habit of messing up when this is done, though. If your column contains numbers (quantitative data), make sure you double-click each column heading and confirm that the Data Type is Numeric and the Modeling Type is Continuous (JMP may have changed the Data Type to Character and the Modeling Type to Nominal).
To get JMP to make confidence intervals for the mean:
Select Analyze, Distribution from the toolbar at top. Highlight the column you are interested in ("drp" in this case) and click the "Y, Columns" button. Click OK. You are now taken to a window showing a histogram and stuff. To get a confidence interval, click the red triangle next to your column variable 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 95% is 0.95). Make sure "Two-sided" is selected. If you are given a value for sigma , the population standard deviation, (and you are in this question) select 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.
To get JMP to test hypotheses for the mean:
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, if you have one (otherwise leave that value blank). 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 if you are given a sigma value to enter or a t statistic if sigma is unknown.
Prob > |z| or Prob > |t| is the two-tailed P-value.
Prob > z or Prob > t is the upper-tailed P-value.
Prob < z or Prob < t is the lower-tailed P-value.
To get rid of any outputs you don't want to copy and paste, click the red triangle and deselect the unwanted things.
To copy and paste the parts of a JMP printout you do want, select the icon on the JMP toolbar that looks like a fat white plus sign "+" (the Selection tool). You can then click various parts of the printout to select the sections you want. Copy and paste into Word or something like that.
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 that, if you are using a program like this, often it loads a "pdf printer" onto your computer. Then, to save your file as pdf, you actually select "print" as though you were going to print your file, then select your "pdf printer" rather than your physical printer in the print options. That will then save your file in pdf form.
Question 8:
If you are making a confidence interval by hand and have to use an unusual level of confidence, look at my question 10 in Lesson 1 for an example how to do that. Also be sure to study how to compute a P-value and test a hypothesis in Lesson 2 of my book. Note, if you are computing a P-value, you can skip Step 2 in my steps to test a hypothesis.