We sample 20 new cars (sedans) and find the average miles per gallon (mpg) to be 26 with a standard deviation of 1.7.
1) If we increase our sample size to 40, what is the standard error of the mean?
In a sample of 100 BSC students, we find that on average students eat at a fastfood restaurant four times a week with a standard deviation of .5.
2) What is the standard error of the mean?
3) If our sample size is 1000, what is the standard error?
In a sample of 212 BSC students, we find that 82% are binge drinkers.
4) If we increase the sample size to 500, what is the standard error of the proportion?
Thirty out of 167 students have been involved in a violent conflict in in the past year.
5) If 90 students reported a violent conflict, what is the standard error of the proportions?
We sample 20 news cars (sedans) and find the average mpg to be 26 with a standard deviation of 1.7.
6) What is the 95% confidence interval (CI)
In a sample of 100 BSC students, we find that on average students eat at a fastfood restaurant four times a week with a standard deviation of .5.
7) What is the 95% CI?
8) What is the 99% CI?
In a sample of 212 BSC students, we find that 82% are bingedrinkers
9) What is the 99% CI?
EXERCISE 2
Use the crosstabulation below to answer questions 13.
Homeowner or Renter of Respondent Crosstabulation
 WHITE  BLACK  OTHER  TOTAL 
Homeowner or renter Owns home Pays rent Other  590 241 23  45 57 4  27 24 3  662 322 28 
Total  852  106  54  1012 
1) How many respondents own a home?
2) Of Whites, what percent own a home?
3) Which of the three groups is most likely to pay rent?
Use the table below to answer questions 4 & 5
Rap Music (3) Respondent’s Sex Crosstabulation

 MALE  FEMALE  TOTAL 
Rap Music (3) Like it Mixed feelings Dislike it  Count % Within Respondent’s sex Count % Within respondent’s sex Count % Within respondent’s sex  56 15.3% 60 16.4% 250 68.3%  55 11.1% 109 22.0% 332 66.9%  111 12.9% 169 19.6% 582 67.5% 
Total  Count % Within respondents sex  366 100.0%  496 100.0%  862 100.0% 
4) Of females, what percent like a rap music?
5) Are males or females more likely to like rap music?
Suppose that we want to know if males are more likely than females to live off campus. Use the data below to construct a crosstabulation table. Be sure to include frequencies, column percent’s, and marginal values.
SEX  RESIDENCE  SEX  RESIDENCE 
Male Female Female Female Male Female Female Male Female Female Female Male  OnCampus OnCampus OnCampus OnCampus OnCampus OnCampus OnCampus OnCampus OnCampus OnCampus OnCampus OnCampus  Female Female Female Female Male Female Female Female Male Female Female  On Campus On Campus On Campus On Campus On Campus On Campus On Campus On Campus On Campus On Campus On Campus 
6) What percent of respondents are male?
7) Of females, what percent live offcampus?
8) Of those who live offcampus, what percent are female?
9) Use the table below to calculate chisquare:
Voting in 1992 election
 Frequency  Percent  Valid Percent  Cumulative percent 
Valid Voted Did not vote Not eligible Refused  659 211 20 5  73.2 23.4 2.2 .6  73.6 23.6 2.2 .6  73.6 97.2 99.4 100.0 
Total Missing DK NA  895 3 2  99.4 .3 .2  100.00  
Total Total  5 900  .6 100.0   
10) Use the table below to calculate chi square:
Classical music (3) Education crosstabulation
  Less Than High School  High School of higher  Total 
Classical music (3) Like it Mixed Feelings Dislike it  Count % Within education Count % Within education Count % Within education  35 30.4% 23 20.0% 57 49.6%  403 54.2% 196 26.3% 145 19.5%  438 51.0% 219 25.5% 202 23.5% 
Total  Count % Within education  115 100.0%  744 100.0%  859 100.0% 
For each of the problems below:
A) Draw a scatterplot.
B) Calculate Pearson’s r
C) Calculate the yintercept, slope, and draw a regression line on the scatterplot.
D)Answer the “prediction” problem
E) Calculate r^{2} and explain what it tells us about the relationship between the variables
F) Calculate the tratio for Pearson’s r and determine the level of significance
11) A researcher wants to learn more about the relationship between the number of miles traveled to work and earnings. She hypothesizes that wealthier employees live outside the city rather than in the city and decides to sample a group of workers from a bank located downtown. She obtains the following data.
EARNINGS IN $ (X)  MILES TRAVELED TO WORK (Y) 
33,250 84,500 66,350 58,425 45,600 67,240 77,900  5 21 6 7 8 14 10 
Prediction problem: How far from the city does an employee earning 50,000 live?
12) A researcher wants to investigate the relationship between social networks and virtual social networks. She predicts that large virtual networks will be associated with large “real” networks. She develops two networking indices to measure networking that range from 0 to 50. Use the data below to access her hypothesis.
VIRTUAL SOCIAL NETWORKING SCORE (X)  “REAL SOCIAL NETWORKING SCORE (Y) 
25 32 16 10 48 22 15 25 34 41  20 10 23 19 37 25 41 25 26 18 
Prediction problem: What is the “real” networking score for a respondent with a virtual networking score of 30?