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### exam1sols

Course: STAT 218, Fall 2009
School: Cal Poly
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Word Count: 900

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218 Exam Stat 1 Solutions Winter 2006 Some questions have different versions, so be sure to find the relevant version for your exam. Frequent flyer question: a) The value 83% is a statistic, because it pertains only to the sample of people who responded to the poll, not to the population of all adult Americans. b) The sampling method is almost certainly biased in favor of yes responses to using a credit card to...

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218 Exam Stat 1 Solutions Winter 2006 Some questions have different versions, so be sure to find the relevant version for your exam. Frequent flyer question: a) The value 83% is a statistic, because it pertains only to the sample of people who responded to the poll, not to the population of all adult Americans. b) The sampling method is almost certainly biased in favor of yes responses to using a credit card to accumulate airline miles, because only people interested in the topic would read the article in the first place, and people who use a credit card to accumulate airline miles would be more likely to be interested in the topic. A common error was not to specify the direction of the bias as it relates to this issue of using a credit card for airline miles. Short answer questions: a) Examples of categorical variables are gender, type of injury, whether the patient has health insurance, whether the patient came in an ambulance. Examples of quantitative variables are waiting time before seeing a doctor, total cost of treatment, number of stitches received. A common error was to give a summary about all patients, such as the number of patients who were treated that day. b) The midrange is not resistant to outliers, because it depends only on the largest and smallest values in the data, so outliers would affect the midrange greatly. The midhinge is resistant to outliers, because it depends only on the quartiles, which are not affected by a few extreme values. c) The sample mean is denoted by y . It is the midpoint of the confidence interval, because the interval is formed by taking the sample mean plus/minus the margin-of-error. In this case the midpoint, and therefore the sample mean, is (6.5+7.7)/2 = 7.1. d) The IQR is the difference between the quartiles, which are the 3rd and 8th values (in order). To make the IQR = 0 requires the middle six scores to be identical. To make the mean greater than the median, include one or two very high values, such as: 60, 60, 60, 60, 60, 60, 60, 60, 100, 100. Here the IQR = 0, median = 60, and mean = 68. To make the mean less than the median, include one or two very low values, such as: 0, 0, 60, 60, 60, 60, 60, 60, 60, 60. Here the IQR = 0, median = 60, and mean = 48. Dog height question: Since we are comparing apples and oranges, we can do so with z-scores. A German Shepherd with a height of 28 inches has a z-score of (28-25)/2.5 = 1.2, indicating that his height is 1.2 standard deviations above the mean. A Sheltie with a height of 18 inches has a z-score of (18-15)/1.5 = 2.0, indicating that his height is 2.0 standard deviations above the mean. Therefore, such a Sheltie is more unusual than such a German Shepherd. A German Shepherd with a height of 22 inches has a z-score of (22-25)/2.5 = -1.2, indicating that height his is 1.2 standard deviations below the mean. A Sheltie with a height of 12 inches has a z-score of (12-15)/1.5 = -2.0, indicating that his height is 2.0 standard deviations below the mean. Therefore, such a Sheltie is more unusual than such a German Shepherd. Body temperature question: a) Because we do not know the population standard deviation , we need to use the sample standard deviation s and therefore a t-interval rather than a z-interval. With a sample size of 65, the degrees of freedom is 64, but with our table we will use 60, giving t* = 1.990. The 95% CI for the population mean body temperature of a healthy adult American female is: 98.105 +/- 1.990(0.699)/sqrt(65), which is 98.105 +/- 0.173, which is ((97.932, 98.278). The 95% CI for the population mean body temperature of a healthy adult American male is: 98.394 +/- 1.990(0.743)/sqrt(65), which is 98.394 +/- 0.184, which is ((97.210, 98.578). b) The symbol represents the mean body temperature among all healthy adult American males/females. c) The 95% CI does not include the value 98.6, suggesting that 98.6 is not a plausible value for the population mean body temperature. d) We are told that the sample was randomly selected, so that condition is met. The second condition requires either a normally distributed population or a large sample size. We can not check normality, but a sample size of 65 is large, so this condition is also met. e) A 90% confidence interval would have the same midpoint, because the midpoint is the sample mean. The width would be smaller, because with a lower confidence level we do not need as wide an interval to be confident of capturing the population mea...

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Cal Poly - STAT - 218
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Cal Poly - STAT - 426
Stat 426 Assignment 7 (due Thur, Mar 13) Topics: Confidence Intervals, Hypothesis Testing, Types of Errors, Power Function, Size, pValue 1. Some student researchers at Cal Poly took a random sample of 100 students and calculated the ratio of backpack
Cal Poly - STAT - 150
Fall, 2008 Stat 150 - Day 7 Scatterplots and AssociationWednesday, Oct. 1Suppose that a criminal leaves behind a footprint so that we can measure the length of his/her foot. Does that enable us to say anything about his/her height? We will collec
Cal Poly - STAT - 321
Fall, 2004 Stat 321 - Day 2 Equal LikelinessTuesday, September 21Activity 2: Random Babies Suppose that on one night at a certain hospital, four mothers (named Johnson, Miller, Smith, and Williams) give birth to baby boys. Each mother gives her c
Cal Poly - STAT - 221
Stat 221Exam 3November 21, 2008Note: Your questions may have appeared in a different order.1. (16 pts, 4 pts each) For the following questions, identify which of the five types of inference procedures would be appropriate. Choose from the fol
Cal Poly - STAT - 252
STAT 252 - Day 29 Introduction to Multiple Regression Example 1: House Prices (cont.) Reconsider yet again the data on price (in thousands of dollars) and size (in square feet) of a random sample of 20 houses sold in Arroyo Grande in 2006-07 (HousePr
Cal Poly - STAT - 218
Stat 218 - Day 4 Five-number summary, Boxplots Five-number summary (FNS): Minimum, Lower Quartile (Q1), Median, Upper Quartile (Q3), Maximum Quartiles are calculated as the median of the values below/above the location of the actual median Example: N
Cal Poly - STAT - 322
Guide to MinitabDr. Jimmy Doi1Introduction to MinitabMinitab is a statistical analysis software package. The software is freely available to all students and is downloadable through the Technology Tab at my.calpoly.edu. When you rst launch Mi
Cal Poly - STAT - 330
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Supplement: The LAG StatementStat 330, Dr. Jimmy A. DoiSupplement: The LAG StatementThis supplement is oered in response to a question a student raised with regard to the lag statement. Please refer to the course notes/textbook for more details
Cal Poly - STAT - 330
Supplement: Permanent Data SetsStat 330, Dr. Jimmy A. DoiSupplement: SAS Permanent Data SetsSuppose we want to import the raw data le age salary.txt which is stored at C:/mySAS/raw data/age salary.txt. Notice that the data is based on three vari
Cal Poly - STAT - 330
OPTIONS FORMCHARStat 330, Dr. Jimmy A. DoiOPTIONS FORMCHARHeres a tip from Professor Russ Lenth (Statistics Department, University of Iowa): How to make SAS tables/output print correctly SAS is set up to use its own fonts, and this causes annoyi
Cal Poly - STAT - 330
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Cal Poly - STAT - 330
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Cal Poly - STAT - 330
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1STAT 330Lecture Set 9 - Basic Statistical PROCs2PROC CHART Proc CHART is used to generate bar charts Choose between vertical bars (vbar) and horizontal bars (hbar) vbar and hbar options include:midpoints = list - specifies midpoints for
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Cal Poly - STAT - 330
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Cal Poly - STAT - 330
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Cal Poly - STAT - 330
STAT 330Output Delivery System (ODS) Prior to version 7 SAS output was designed for a traditional line-printer limited to monospace fonts and not as flexible Version 7 and up now contain the ODS Lecture Set 12 - Bells and Whistles Where do we
Cal Poly - STAT - 330
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Cal Poly - STAT - 330
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Cal Poly - STAT - 330
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Cal Poly - STAT - 330
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Stat 330: Assignment 4 Due: Wednesday, January 28, 2009 at 11:59:59 pm 1. A company that works with various military contracts (too confidential to even be discussed in detail here) has a data file that contains basic contract initiation information
Cal Poly - STAT - 330
Stat 330: Assignment 2 Due: Wednesday, January 14, 2009 at 11:59:59 pm1. Data were collected on prices in cents per pound received by fishermen and vessel owners for various species of fish and shellfish in 1970 and 1980. The variables in this file
Cal Poly - STAT - 330
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Cal Poly - STAT - 330
1STAT 330Lecture Set 10 More Statistical PROCs2Keeping Track of Stats Can use out= option with most proc's to keep your statistics in a SAS data set useful for presentation or reporting can manipulate these statistics if need be in most
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12STAT 218Sampling DistributionsLecture Set 4 Sampling Distributions Definition: Sampling Variability is the variability among random samples from the same population. A probability distribution that characterizes some aspect of sampling
Cal Poly - STAT - 218
Sampling Distributions Definition: Sampling Variability is the variability among random samples from the same population.A probability distribution that characterizes some aspect of sampling variability is calledThe Meta-Experiment A meta-experim
Cal Poly - STAT - 218
12STAT 218ApplicationLecture Set 8 More on the T Test and the Wilcoxon-Mann-Whitney TestExample: Nine observations of surface soil pH were made two different locations. Does the data suggest that the true mean soil pH values differ for the
Cal Poly - STAT - 218
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Cal Poly - STAT - 218
1STAT 218Statistical Inference Concerning 1 How can we use statistical inference in regression?2Lecture Set 13 More Regression Suppose we would like to investigate the relationship between X and Y If X is telling us nothing about Y, wha
Cal Poly - STAT - 218
12STAT 218Quantitative DataLecture Set 5 Sampling Distribution for the Mean and Introduction to Confidence Intervals More complex than dichotomous data Sample and populations for quantitative data can be described in various ways: mean, m
Cal Poly - STAT - 218
1STAT 218Planning a Study to Estimate It is important before you begin collecting data to consider whether the estimates will be sufficiently precise. Two factors to consider:2Lecture Set 6 Sample Size Calculations and Confidence Interval
Cal Poly - STAT - 218
Two Way ANOVA Name the type of two way ANOVA discussed in our text book.What is the point of blocking?Can blocks consist of more than two observations?Name the three parts that the total variability is split into.Completely RandomizedSS(betw
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Cal Poly - STAT - 217
Comparative Bar Chars What is the main purpose of a comparative bar chart?Example: According to the Cal Poly Fact Book 2003-2004 the enrollment by gender and college are as follows.Chart of Enrollment vs College, Gender90Percent of Enrollment
Cal Poly - STAT - 217
Name: STAT 217 HW addition Chapter 5 1. Consider the following data collected on the yield (in bushels) for 19 equal sized plots planted in tomatoes for that were sprayed with different amounts of fertilizer. Amount of Fertilizer (pounds per plot) 25
Cal Poly - STAT - 217
12STAT 217Planning a Study Before we analyze data, much thought and planning should go into how to collect the data Without quality information our conclusions will not mean muchLecture Set 2 Sampling and Design Six steps of the data ana
Cal Poly - STAT - 217
Choose the appropriate scenario: independent, paired, chi-square/goodness of fit, chi-square/contingency table, Oneway ANOVA, Two-way ANOVA, or regression. Is Friday the 13th an unusually unlucky day, or is this just superstition? How do superstition
Cal Poly - STAT - 217
Name: STAT 217 HW addition Chapter 8 1. The serum cholesterol of a population of 18-year-olds is approximately normally distributed with a mean of 176 mg/dLi and a standard deviation of 30 mg/dLi. What percentage of the 18-year-olds have a serum chol
Cal Poly - STAT - 217
Name: STAT 217 HW addition Chapter 151. The following ANOVA table is only partially completed. a. Complete the table.6Plot A5Individual Value PlotSource Treatment Error TotalDF 2SSMS 46.67F _P 0.0004330.00 1421 A B Cb.
Cal Poly - STAT - 217
Name: STAT 217 HW addition Chapters 3 and 41.For the following histograms, estimate the mean and median.Histogram of C114 12 10Histogram of C235 30 25 Frequency 20 15 10 5Frequency8 6 4 2 036424854 C1606672780012
Cal Poly - STAT - 217
Name: STAT 217 HW addition Chapter 4 1. Which of the boxplots below is represented by the histogram? Justify your answer.Boxplot of 1, 2, 3, 412 1 10 2 8 6 4 2 0Histogram3401020 Data304050Frequency01020 230402.Whic
Cal Poly - STAT - 217
Sampling Variability Do we expect that the sample mean x from a random sample will be exactly equal to the population mean ? ExplainWhat if we gathered another random sample of the same size, would this x be exactly equal to ? Explain.Would the
Cal Poly - STAT - 217
12STAT 217Basic Probability We typically think of probability as the chance that an event will occur Probability plays an important role in statistics because it allows us to make decisions with confidence We can think of probability as the
Cal Poly - STAT - 217
Statistics Example What do you think of when you hear statistics?What are three important reasons to learn statistics?Definition: Statistics is the scientific discipline that provides methods to help us make sense of data. To utilize statistics w
Cal Poly - STAT - 217
12STAT 217One Variable Categorical Data So far our experience with hypothesis testing and categorical data is limited to one dichotomous variable We need to expand our thinking to deal with more than two categories The Chi Square Goodness of
Cal Poly - STAT - 217
12STAT 217Correlation Analyze the relationship, if any, between variables x and y by examining the linear strength between them Correlation is a numerical measure of this linear relationshipLecture Set 5 Summary of Bivariate Data can be
Cal Poly - STAT - 217
DISCLAIMER: The size and question content of this review should not be considered an exact replication of the exam. The questions on the exam will be different. The purpose here is to supply you with more questions to practice with. In my opinion the
Cal Poly - STAT - 217
National paper company must purchase a new machine for producing cardboard boxes. The company must choose between two machines, machine 1 and machine 2. Since both machines produce boxes of equal quality, the company would like to choose the new mach
Cal Poly - STAT - 217
One Variable Categorical Data What does one sample data mean?What type of test would we use to compare a categorical variable with more than two groups?What does k stand for?Goodness of Fit Test What are the general forms of the hypotheses? Ho: