Math Statistics

Written Homework # 2

I have attempted this assignment honestly and the material submitted is my own work. I have only worked with the other group members listed on this page. I have not copied from any source, and cited any materials I have used outside of lecture notes and the textbook.

Names: Signatures:

Chapter Objectives (Chapters 6, 7, 8): Estimate shape, direction, and strength of correlation

Use technology to compute correlation and regression lines Interpret a regression model and use it to extrapolate information Hypothesize about the reason for a relationship between data sets

Due Date: Monday, July 10

Statistics Summer 2017

1 Choose two bivariate data sets, one with positive linear correlation and one with negative linear correlation. Collect at least 20 data pairs for each. Below are some examples, feel free to choose your own. Avoid using ”time” as one of your variable.

• “Seahawks wins (x) vs Annual Rainfall in Seattle (y)”

• “Overall Quality (x) vs Level of Difficulty (y) on Rate my Professor”

• “Population of a city (x) vs Number of Starbucks (y)”

For each of your data sets:

(a) Use technology to plot your data set on a scatterplot. Make decisions about any outliers. Note if your data is possibly non-linear. (if the data set is definitely non-linear, find a new data set)

(b) Use technology to compute the correlation. Classify the correlation as strong/weak, positive/negative (or make a note that correlation may not be linear).

(c) Use technology to compute the equation of the line of best-fit. Describe what the slope of this line tells you. Use units. Describe what the y-intercept of this line tells you.

(d) When is this model valid? When does it break down and why?

(e) Use your model to extrapolate two data points not in your original data set.

(f) Describe the relationship between these two data sets. Is there cause and effect? Reverse cause and effect? Lurking variable? Coincidence?

(g) Summarize your findings.

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