Stat II Jargon Central Limit Theorem, Type I and Type II error, P-value, Biased estimation, mean squared error. Ch. 5: Bivariate data, Define error in regression, Problem of common response, Problem of confounding, What criterion is used in regression (Hint: least squares minimizes error sum of squares) Slope of a regression, Intercept of a regression, What are the limits in which a simple correlation coefficient must lie? ANS(-1 to 1) What test should one use for the overall regression model? What test for individual regression coefficients? What is R-square and Adjusted R-square? What is the command for regression of y on x1 and x2? ANS: lm(y~x1+x2) Give two R commands, which run above regression and print the main regression results. reg1=lm(y~x1+x2) summary(reg1) In the above command how to ensure that the regression line does go through the origin (no intercept)? ANS: lm(y~x1+x2-1) What is the R command to compute the correlation coefficient between x1 and x2 and test it? (ANS: cor.test(x1,x2) ) What is the R command to test the null that the mean of y is zero? (ANS: t.test(y) ) What is the R command for analysis of variance? (ANS: anova(lm(y~X1+x2)) ) What is the R package needed to do basic descriptive statistics conveniently? (ANS: fBasics) What are the R commands for computing the mean and standard deviation of y? mean(y) sd(y) What are the R commands for: 1) Reading data ANS read.table(file="filename") 2) Running regressions including multiple regressions ANS: lm(y~X1+x2) 3) Descriptive stats (which package do you use and how?) basicStats(y) 5) Plots and plot headings plot(x,y, main="Heading") 6) Confidence intervals ANS: confint(lm(y~X1+x2)) 7) Analysis of variance. ANS: anova(lm(y~X1+x2)) 8) Finding the residuals of a regression ANS: resid(lm(y~X1+x2)) 9) Printing the results of regression to the screen.ANS: summary(lm(y~X1+x2)) 10) Computing the portion of test stats which comes from z, t and F tables. qnorm, qt, qf 11) Computing the portion of p-value statistics which comes from z, t and F tables.pnorm, pt, fp #Finding CRITICAL VALUES from t table and F table using qt and qf alp=0.05 #the alpha value alpby2=alp/2 #defines alpha by 2 for typical t test dft=length(y)-3 #defines degrees of freedom for t qt(alpby2,df=dft)#quantile of t distribution qf(alp, df1=2, df2=dft, lower.tail=F)#quantile of F distribution #Finding p-values from t table and F table using pt and pf #pvalues are already given by R #for example t value in summary table is -2.306 for the pie-sales example pt(-2.306,df=dft, lower.tail=T)*2 # we multiply tail area by 2 to get the p value= 0.03976325 #doubling is needed because t test is two-sided Part 2 of the final will have 3 questions 1) Use excel to do anova worth 2% 2) Given a payoff table, find maximax, maximin, minimax regret, max expected value and minimum expected regret worth 3% 3) 6 questions from jargon worth 3% see http://www.fordham.edu/economics/vinod/jargon2.txt file at my website for possible list for the third question.