STATISTICS TRIVIAL PURSUIT (SORT OF) FOR REVIEW (MATH 17) COLORS AND CATEGORIES Blue – Basic Graphs and Descriptive Statistics Pink – Assumptions (cumulative) Yellow – Statistical Theory and History Brown – Interpretations Green – Last 1/3 Inference Orange – Other Hypothesis Testing Related BLUE 1 What are the descriptive statistics that are sensitive to outliers? BLUE 2 Provide the name and primary purpose of this graph. BLUE 3 Provide a basic description of the distribution of this variable from its graph (remember there are 3 things to describe). BLUE 4 What are the descriptive statistics used in the creation of a boxplot? BLUE 5 Name the rule used to compute outliers, and describe how to apply it. BLUE 6 Name graphs that are appropriate to display categorical variables, and state whether or not you should discuss the shape of distributions based on those graphs. BLUE 7 Compare/contrast these 2 distributions based on the plot. BLUE 8 A standard deviation of a measurement in feet is 3.4 feet, from a sample with a mean of 29.2. Interpret the standard deviation. BLUE 9 This plot is part of the preliminary analysis for …. BLUE 10 If there was a high outlier in the distribution of a particular variable, and it was removed, what descriptive statistics are likely (or certain) to change to a significant extent? PINK 1 What is the assumption that all chi-square tests have in common? PINK 2 What is the assumption related to sample sizes for a 2 sample z-test? PINK 3 What is the assumption related to sample size when constructing a confidence interval for p? PINK 4 What are the specifics of the nearly normal condition for a paired t-test? PINK 5 What are the specifics of the nearly normal condition for ANOVA? PINK 6 What are the specifics of the 2 assumptions in regression related to error terms? PINK 7 You are told that the randomization and independence condition is met for a sample of high school students who were asked how much money they received for their most recent birthday. Describe what the randomization and independence assumption means in this context. PINK 8 What are some example tests where assumptions related to normality are NOT required? PINK 9 What are the specifics of the nearly normal condition for a 2-sample t-test? PINK 10 What is the assumption that all tests/CIs have in common but which (since it is common to all) Prof. Wagaman doesn’t require that you write down when you list assumptions? YELLOW 1 What is a sampling distribution for a statistic? (conceptually) YELLOW 2 (Fill in at least 3 of the blanks for credit) The t distribution was discovered by ___________ who published under the pseudonym ____________. He discovered the t distribution while working for _____________ in Ireland. Specifically he was working in the field of ______________ (2 words, but one blank) and was primarily responsible for checking out _________, one of their many products. YELLOW 3 What does the Central Limit Theorem say? YELLOW 4 How are z-scores computed, and what are they useful for? (variety of answers) YELLOW 5 When sampling distributions have standard deviations that involve unknown parameters, and we plug in estimates for those parameters, we obtain what value(s)? YELLOW 6 Suppose 2 random variables X and Y are independent. X has mean 6 and standard deviation 3. Y has mean 14 and standard deviation 4. What are the values of the mean and standard deviation of X+Y? YELLOW 7 What are the differences between a chi-square test of homogeneity and a chi-square test of independence? YELLOW 8 What are the three types of bias in sampling? YELLOW 9 If you are designing an experiment and you have 3 different drugs you want to try, and you want to try them at 2 different doses each (1 pill or 2 pills daily), and you want to include (a) placebo group(s), how many treatments are there in your experiment? YELLOW 10 Name and describe two different sampling techniques. BROWN 1 Running a hypothesis test for slope equal to 0 or not, you obtain a t-test statistic value of -2.14. Interpret this test statistic. BROWN 2 A linear regression results in an R-squared value of .81. Assuming linear regression was appropriate, interpret this R-square in terms of general X and Y variables. BROWN 3 A random sample of n=16 observations yields an s=24 (sample standard deviation). What is the numerical value of the standard error of the sample mean? Also, interpret this value. BROWN 4 Describe what is wrong with the statement: “A p-value is the probability that the null hypothesis is true.” BROWN 5 A 95% confidence interval for a mean weight of a new dog breed goes from (25.2, 34.6) pounds. Interpret the confidence interval given here. BROWN 6 A regression results in an s_e value of 3.46. The y-axis goes from 36 to 109. What does the s_e value represent, and what does it tell you about how well the regression does? BROWN 7 A p-value for an ANOVA testing for equality of 5 means with an F of 24.56 is .0359. Interpret this p-value. BROWN 8 A 95% confidence interval for a mean weight of a new dog breed goes from (25.2, 34.6) pounds. Interpret the confidence level used here. BROWN 9 A conclusion in a t-test of mu=150 vs. mu>150 is given as: Our evidence is not inconsistent with our null hypothesis. How should this conclusion be changed to be correct? BROWN 10 A p-value for a two-sided two sample z-test is .1470 based on a Z of 1.45. Interpret this p-value. GREEN 1 Which set(s) of graphs indicate it would NOT be appropriate to perform an ANOVA? Explain. GREEN 2 You want to know if the distribution of class year among Reunion workers is equally split among first-years, sophomores, and juniors. What test is appropriate? (Note, I am assuming that seniors can’t get hired to work Reunion, if they can, change this to equally split among all four class years). GREEN 3 An ANOVA where the null hypothesis is rejected results in multiple comparisons of: Estimate lwr upr 2-1 4.146737 -2.737867 11.031342 3-1 -3.742933 -10.627537 3.141671 3-2 -7.889670 -14.774274 -1.005066 Summarize what this multiple comparisons shows you. GREEN 4 If you wanted to know whether or not there is a significant association between heart rate and weight in rats, what statistical procedure would you perform? GREEN 5 You want to compare the means of 4 groups. Describe why you would want to do an ANOVA rather than 6 t-tests to compare all pairs of means. GREEN 6 You want to know if there is an association between t-shirt size (S,M,L,etc.) and class year at Amherst. What is the appropriate statistical procedure to perform? GREEN 7 You want to know if a higher proportion of underclassmen have corrective lenses compared to upperclassmen. Explain why there is no appropriate chi-square test for this situation. What analysis could you run? GREEN 8 A balanced ANOVA is an ANOVA where…. GREEN 9 Describe the similarities and differences in finding p-values for ANOVA and chi-square. GREEN 10 A scatterplot for regression is given as: R also reports an Rsquared value of .81 What is the correlation between X and Y? ORANGE 1 What is power and how would you increase it for a hypothesis test? ORANGE 2 What is a Type I error? ORANGE 3 If given a significance level of .035, for what pvalues would you reject the null hypothesis? ORANGE 4 Explain the difference between practically significant results and statistically significant results. ORANGE 5 Most of the tests we learned in class were ______________ tests. If certain assumptions related to them are not met, you can run ________________ tests, one example of which is ________________________. (Fill-in at least 1 blank). ORANGE 6 Hypothesis tests and confidence intervals are based on an understanding of the __________________ _______________________ (two words) of statistics. ORANGE 7 You are performing a t-test for mu=60 versus a 2sided alternative and all conditions are satisfied. What is the expected value of your test statistic under the null hypothesis? ORANGE 8 You are testing for p=.4 vs. p>.4 and all conditions are satisfied. Your sample results in 30 yes replies out of 100 responses. What can you say about your p-value for this test? ORANGE 9 In order to use a confidence interval to do a onesided t-test with a significance level of .05, what confidence level would need to be used? ORANGE 10 You are testing for mu=50 vs. mu>50, and the appropriate confidence interval is (52,64). Can you reject your null hypothesis? Explain. REMINDER: Final Exam is Monday, May 9th, 9 am -12 noon in SM 207 You can bring a two-sided page of notes and calculator, plus pen/pencils. Office Hours: Thursday – 2-4 Friday – 1-4 Sunday – 2-4 pm, SM 206 or 207 Good luck studying! THANKS FOR A GREAT SEMESTER! Math dept. end of semester picnic is Saturday from 12-2 at the Alumni House