Sampling Methods and Biases
A grocery store wants to know if its customers think the store is clean. They decide to
ask every 6th customer for their opinion. What sampling method is this?
a. Cluster
b. Stratified Random
c. SRS
d. Systemic
Systemic
What is the most common favorite movie?
Romance
The employees in one department had to provide a report giving the total mileage for the year for any work-related travel. Their mileages are shown below:
639 622 344 648 354 348 360 598 479 482
1a) Find the mean
487.4
The number of cars passing through a bank drive-thru during each 15-minute period was recorded. The results
are shown below:
27 29 27 30 30 27 32 29 14 27 26
33 27 22 17 21 29 29 37 33 29 33
2b) Find the sample standard deviation
5.36
The employees in one department had to provide a report giving total mileage for the year for any work-related
travel. Their mileages are shown below:
639 622 344 648 354 348 360 598 479 482
1c) Find the 5 number summary
min=344, Q1=354, med=480.5, Q3=622, max=648
We did a study on how often people reply to surveys in the mail. Shockingly, 97% of people respond to surveys and only 3% throw surveys in the trash. What kind of bias is this?
Nonresponse Bias
Social Acceptability Bias
Sampling Bias
Voluntary Response Bias
Nonresponse Bias
Generate a frequency distribution based on this data with a class width of (0.1)
0.45, 0.67, 0.54, 0.12, 0.13, 0.98, 0.86, 0.68, 0.45
Ipad!
The number of cars passing through a bank drive-thru during each 15-minute period was recorded. The results
are shown below:
27 29 27 30 30 27 32 29 14 27 26
33 27 22 17 21 29 29 37 33 29 33
2a) Find the mean
27.82
The employees in one department had to provide a report giving total mileage for the year for any work-related
travel. Their mileages are shown below:
639 622 344 648 354 348 360 598 479 482
1b) Find the sample standard deviation
130.49
The mean test score on the Chapter 5 mathematics test was 52, with a standard deviation of 14. How many standard deviations from the mean is a test score of 95?
3.07 or 3.07 standard deviations above the mean
True or False: movie ratings (G, PG, R, etc.) are categorical & ordinal
True
What is the class width of this data?
0.6
In what interval should you expect the central 95% of IQ scores to be found?
68 – 132
Which class has the set of GPAs that is skewed left?
Sophomores
Group 1: The weight of nine defensive linemen were 300, 300, 295, 255, 298, 298, 300, 310, 300
6a) Give the Five Number Summary for group 1.
Defensive linemen: min = 255, Q1 = 296.5, med = 300, Q3= 300, max = 310
A hospital in Georgia wants to collect data on asthma. They decide to collect data from 5 different hospitals around the state and collect data on all asthma patients there. What kind of sampling method is this?
Cluster
Stratified Random
Voluntary
Systemic
Cluster
True or False:
This graph is a bar chart
False
What is the process on your calculator to calculate the Sample Standard Deviation?
STAT - Edit - Enter Values into list
STAT - Calc - Enter List # of data - Sx value
Which class had the highest median GPA, and what is the approximate value of that GPA?
Sophomores,
3.5
Group 1: The weight of nine defensive linemen were 300, 300, 295, 255, 298, 298, 300, 310, 300
6b) What is the IQR for the defensive linemen?
3.5
True or False: the number of votes per candidate is quantitative & continuous
False, quantitative & discrete
Create a stem-and-leaf plot with this data:
250 200 200 209 280 253 257 292 300
Ipad
The number of cars passing through a bank drive-thru during each 15-minute period was recorded. The results
are shown below:
27 29 27 30 30 27 32 29 14 27 26
Find the mode
27
Describe the distribution of this data.
Skewed Left
The average number of days absent per student per year at a local high school is 17 days with a standard
deviation of 4 days. How many standard deviations from the mean would represent 6 absent days? (Find the z-score)
- 2.75 or 2.75 standard deviations below the mean