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Unformatted text preview: Statistics 10: Week 3, Session 2 Lecture Notes
Professor Esfandiari Problem one: Given the following three plots and table, answer the questions posed. Y = Attitude toward seeking preventive care for breast cancer (scale 0—100)
X = Knowledge of breast cancer (Scale of 0—100) ' r yx = 0.80
° bl = 0.75
° b0 = 15.95 a) What are the independent/predictor and dependent/outcome variables and are they
qualitative or quantitative? b) What does r yx = 0.80 Show? 0) Given the above data, Terri concluded that acquiring more knowledge of breast cancer
will lead to doing more mammograms? Is she right? Yes or no and why? (1) Write the least square regression line and interpret the slope and the intercept within
context. e) Interpret R A2 f) What do you conclude from plot one with respect to regression assumptions? h) What do you conclude from plot two with respect to regression assumptions? i) What is the difference between plots 2 and 3 and what do they have in common? What
does plot 3 show that plot 2 does not? j) Are there any leverage points? Why yes and why not? k) Are there any outliers? Why yes and why not? 1) If I remove the four point around which I have placed a circle in graph one, do you
expect the coefficient of correlation to change and slope of the regression line to change
or not and explain why? Plot one 100. 0 0 D
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1 333mg uwNmEmucﬁm «3.00000 £00 30 03 D £10 knowﬂedge ofbreastcancer Problem two:
The following scatterplot has resulted from the Gestation data reported on problem 25
page 249 of chapter nine. Ch09_Gestation.txt Scatter Plot 700 600 aye
01
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O Geetatian d
00
O
O 0 20 4O 60 80
Life_Expectancy_yrs Gestation = length of time from conception to birth
All of the points in the above scatterplot represent mammals. The point with life
expectancy = 80 belongs to a human. Question to be answered?
Is the point related to humans, inﬂuential or not? What would happen to coefficient of
correlation and slope if we remove this point? Problem three: Plot the following data.
Y X
20.00 20 .00
20 .00 20 .00
21 .00 25 .00
25 .00 30.00
28.00 15.00
28 .00 16.00
25 .00 32.00
25.00 29.00
32.00 20.00
34.00 20.00
35.00 20 .00
35 .00 30.00
35 .00 10.00
40.00 18 .00
38 .00 22.00
35.00 30.00
10.00 70.00 a) What would happen to correlation and slope if we remove (10,70) and why? N0
calculations are necessary. b) Do you consider (10,70) to be leverage or outlier or both and why? Problem 4: Interpret the following plot. Jerry was hired to work on this data and he reported the
coefficient of correlation between years since 1950 and rate (%) to be 0.70. If you were
looking for somebody to work on your data, would you hire him? Explain why yes or
why not. Ch09_lntrest_Rates19502005.txt Scatter Plot‘ H1950 1960 1970 1980 1990 2000 2010
Year ...
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 Fall '11
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 Scatter plot

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