Statistics Chapter 3 Exam Questions and Answers Latest Update 2024 Already Passed
Procedure with 2 variable statistics - Answers 1.) Plot data and calculate numerical summaries
2.) Look for overall patterns and deviations from those patterns
3.) When there's a regular overall pattern, use a si...
Procedure with 2 variable statistics - Answers 1.) Plot data and calculate numerical summaries
2.) Look for overall patterns and deviations from those patterns
3.) When there's a regular overall pattern, use a simplified model to describe it
Response variable - Answers Measures an outcome of a study
Explanatory variable - Answers May help explain or influence changes in a response variable
Specific values of variables - Answers It is easiest to identify explanatory and response variables when
we actually specify values of one variable to see how it affects another variable.
Causation - Answers Often we want to know whether changes in the explanatory variable causes a
change in the response variable. Remember, correlation does NOT imply causation.
Graph for displaying relationship between two quantitative variables - Answers Scatterplot
Scatterplot - Answers Shows the relationship between two quantitative variables measured on the same
individuals. The values of one variable (explanatory variable) appear on the horizontal axis and the
values of the other variable (response variable) appear on the vertical axis. Each individual in the data
appears as a point in the graph.
Explanatory-response relationship - Answers Always plot explanatory variable if there is one on
horizontal axis (x axis) of the scatterplot. We usually call the explanatory variable x and the response
variable y. If there is no explanatory-response distinction, either variable can go on the horizontal axis.
How to make a scatterplot - Answers 1.) Decide which variable should go on each axis
2.) Label and scale your axes
- Don't start at (0,0)
- Start scale to highlight main body of points
3.) Title your plot
4.) Plot individual data values
How to examine scatterplots - Answers Look for the overall pattern and striking departures from that
pattern.
1.) To describe the OVERALL PATTERN of a scatterplot, discuss the direction/trend, the form/shape,
clusters and the strength of the relationship
, 2.) To describe DEPARTURES from the OVERALL PATTERN discuss outliers (an individual that falls outside
the overall pattern of the relationship)
Form/shape - Answers The general shape of the graph
Ex: linear relationships/curved relationships/outliers/clusters
Direction/trend - Answers Draw oval around data and find the slope of the major axis: negative slope
means negative trend while positive slope means positive trend
If relationship has a clear direction, we speak of positive association (high values of one variable tend to
occur together) or negative association (high values of one variable tend to occur with low values of the
other variable)
Strength (heteroscedasticity) - Answers How scattered is the data (based on the oval)
How close the points in a scatterplot lie to a simple form such as a line
- Thin hot dog shape = strong
- Football shape = moderate
- Basketball shape = week
- Fan out = differs for different values of explanatory variable
*Correlation coefficient
Cluster - Answers There are a bunch of data points together
- Name ranges of each variable where cluster appears
Outlier - Answers There's a lot of white space around the data point
- Outlier in response variable (y)
- Outlier in explanatory variable
- Outlier in both
- Outlier b/c doesn't follow the overall pattern/trend
Positive association - Answers Positive association, negative association
Two variables have a positive association when above-average values of one tend to accompany above-
average values of the other, and when below-average values also tend to occur together.
Negative association - Answers Two variables have a negative association when above-average values of
one tend to accompany bleow-average values of the other
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller TutorJosh. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $8.29. You're not tied to anything after your purchase.
