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There is still time to register for my Exam Prep seminar!
Space is available. $40 at the door. |
My Midterm Exam Prep Seminar for Stat 1000 is Saturday, March 7.
I will be working through the two sample midterm exams the department will post
online.
Midterm Exam Prep Seminar for Stat 1000
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$40, pay at the door
Saturday, March 7
9:00 am to 6:00pm
Room 100, St. Paul's College, UM campus
Have you tried my Audio Lectures?
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Don't have my book or audio lectures? You can download a free sample of my book and audio lectures containing Lesson 1:
Tips you may have missed:
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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:
You will have to study both Lesson 6: The Binomial Distribution and Lesson 7: The Distribution of the Sample Mean in my Basic Stats 1 book to prepare for this assignment. NOTE: You need only study up to the
end of question 7 (end of page 392) in Lesson 6 at this time (the rest of Lesson 6 will be covered after the second midterm). You also need only study to the end of question 7 in Lesson 7 (end of page 447). The section on control charts has been removed from the course.
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.
A Warning about StatsPortal
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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.
I tell you the definitions of parameters and statistics at the start of Lesson 4 of my book and I repeat them again in Lesson 7 and illustrate with my question 1.
Although I disagree with them entirely (and I know I am right), last term the profs insisted that you say n, the sample size, is a statistic.
Note that although n is a sample size, n is a parameter. This is not a contradiction from what I tell you at the
start of Lesson 4 and 7. It is still true that, when you are given n, you are being alerted that a sample has been selected, and any values they compute from that sample, by definition, will be statistics. However, the n, itself, is considered a parameter. One obvious way to see this is, as any textbook will tell you, and as I say in Lesson 6, the parameters of the binomial distribution are n and
p.
I will go to my grave asserting that n is a parameter, but I believe, in this course, you are told to consider n a statistic.
Question 2: Is it Binomial?
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Lesson 6. If you are ever asked to decide if a particular situation is binomial or not, remember, to be binomial, four conditions must be satisfied: - There must be a fixed number of trials, n.
- Each trial
can have only two possible outcomes, success or failure, and the probability of success on each trial must have a constant value, p.
- Each trial must be independent.
- X, the number of successes, is a discrete random variable where X = 0, 1, 2, ... n.
Hints: - If you are reading off numbers from a randomly selected row in the random number table, note that every row has
40 digits. That is like 40 trials looking for whatever digit you may be looking for. What is the probability that, at any moment on the table, the next digit is a 0, or a 1, or a 2, etc..
- If you are selecting objects, are you sampling with replacement (independent trials) or without replacement (dependent trials)?
- If you are given a Normal population, but are selecting a sample of size n, and want to see how many
of them are greater than 62 (for example), THAT IS A BINOMIAL DISTRIBUTION! You can use Table A to find what proportion are greater than 62. That is your p. Each trial, the person/thing either is greater than 62, or they are not. And the chance they are greater than 62 is p, the proportion you shaded on the bell curve.
- If you are ever conducting trials until you get a desired result, that will never
be binomial because you do not have a fixed number of trials, n. For example, if I am rolling a die until I get a six and X= the number of rolls until I get a six, that is not binomial, because there are no fixed number of trials, n.
Question 3: Airline Flights
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I introduce the formula for mean and standard deviation of a binomial distribution in my Lesson 6, question 7. Note that the mean of X is np and the variance of X is np(1-p).
Be careful that you are using the correct n and p for each question since they keep switching which flight and how many years and flights they are talking about. Note that n is the total number of flights he has taken to a specific destination during the time period, not just the number that arrive on time. I think they want you to understand that he is making 5 trips each year, and on each trip he has to
take 3 flights. So there are five first flights, five second flights and five third flights each year.
Therefore, if the question is talking about Flight 1 for one year, then n=5. Similarly, for Flight 2 or Flight 3. However, if the question is talking about 2 years, then n is doubled.
This is Lesson 7 stuff. You have to always be asking yourself, "Is the problem talking about one individual score X? Or, is it talking about the mean of n scores, x-bar?" If it is
talking about just one score X, is X normally distributed? If it is talking about the mean of n scores, x-bar, can we assume x-bar is normally distributed? Why or why not? If we can assume these are normally distributed, then be careful to use the proper standardizing formula. Either the X-Bell Curve formula or the x-Bar Bell Curve formula.
Look at
my questions 4 through 7 in Lesson 7 for examples. Especially take note of my questions 6 and 7 if they give you a total amount in a question as they do in part (c).
Be careful in part (d). They are talking about the mean of a sample of some size n (the value of n varies for different
students). Thus, you must compute the mean of x-bar and the standard deviation of x-bar, which are mu and sigma divide by square root n first, then use those values for your 68-95-99.7 rule. Make sure you put the smaller answer first.
Approach this just like the previous question. Ask yourself the same questions.
Question 6: Probabilities
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Your probabilities are exact if you know for sure that the distribution is normal. However, if you were only able to say the distribution is approximately normal, then your probabilities are only approximate. This question boils down to,
"Were you told the population is normal?" If you know for a fact that the population is normal, you can compute exact probabilities. If you do not, the best you can do is compute approximate probabilities.
Approach this just like questions 4 and 5 above. Ask yourself the same questions.
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