STT 215 FINAL EXAM QUESTIONS AND
ANSWERS
What are the three main components of statistics for answering a statistical
question?
Design, Description, and inference
The group that participates in a study is called a what? What do we try to
describe with this group?
the group is the sample, and we use the sample to describe the population
The best way to eliminate a chance for bias in a study is by using a ________
sample
Random
A study can often be thrown off by "hidden" variables. What are these variables
called?
Lurking variables
If I were to ask a group of math majors their opinions on math their responses
probably wouldn't be agood descriptor for the general public. What kind of bias
did my study introduce?
Sample bias
What are the three components to a good experiment?
Control, randomization, replication
If I gave the class a new pill that claimed to make everyone better at math
before this exam and everyone scored a 100, why can I not say, with
confidence, that the pill worked? What else would I need to include in the study
to be able to judge if it worked or not?
You can't say the pill worked because there is only one trial and no control. We
need a control to judge the effectiveness
, Classify the following variables as categorical or quantitative.
• Whether or not a person has glasses.
• The color of a stoplight.
• How many stoplights you hit on the way here today.
1. Categorical
2.Categorical
3.Quantitative
Classify the following as continuous or discrete.
• How many stoplights you hit on the way here today.
• The number of people in class today.
• How long a roadtrip might take.
1.Discrete
2.Discrete
3.Continuous
Use the Empirical rule for the following.
• How much data falls within two standard deviations of the mean?
• How much data falls out of one standard deviation of the mean?
• How much data falls between one standard deviation below the mean and two
standard deviationsabove the mean?
1. 95%
2. 32%
3. 1 below is 34% and 2 above is 47.5%
For some distribution the mean is 85 and the standard deviation is 6. Find the z-
score for 97 and findthe z-score for 80.
Observation-mean/Standard deviation
97-85/6=2
97-80/6=-5/6
Does the following table represent a valid distribution?
All have to add to be exactly 1
This is not a valid representation because all the data add to be over 1
ANSWERS
What are the three main components of statistics for answering a statistical
question?
Design, Description, and inference
The group that participates in a study is called a what? What do we try to
describe with this group?
the group is the sample, and we use the sample to describe the population
The best way to eliminate a chance for bias in a study is by using a ________
sample
Random
A study can often be thrown off by "hidden" variables. What are these variables
called?
Lurking variables
If I were to ask a group of math majors their opinions on math their responses
probably wouldn't be agood descriptor for the general public. What kind of bias
did my study introduce?
Sample bias
What are the three components to a good experiment?
Control, randomization, replication
If I gave the class a new pill that claimed to make everyone better at math
before this exam and everyone scored a 100, why can I not say, with
confidence, that the pill worked? What else would I need to include in the study
to be able to judge if it worked or not?
You can't say the pill worked because there is only one trial and no control. We
need a control to judge the effectiveness
, Classify the following variables as categorical or quantitative.
• Whether or not a person has glasses.
• The color of a stoplight.
• How many stoplights you hit on the way here today.
1. Categorical
2.Categorical
3.Quantitative
Classify the following as continuous or discrete.
• How many stoplights you hit on the way here today.
• The number of people in class today.
• How long a roadtrip might take.
1.Discrete
2.Discrete
3.Continuous
Use the Empirical rule for the following.
• How much data falls within two standard deviations of the mean?
• How much data falls out of one standard deviation of the mean?
• How much data falls between one standard deviation below the mean and two
standard deviationsabove the mean?
1. 95%
2. 32%
3. 1 below is 34% and 2 above is 47.5%
For some distribution the mean is 85 and the standard deviation is 6. Find the z-
score for 97 and findthe z-score for 80.
Observation-mean/Standard deviation
97-85/6=2
97-80/6=-5/6
Does the following table represent a valid distribution?
All have to add to be exactly 1
This is not a valid representation because all the data add to be over 1
