Lab 4

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South Dakota State University *

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281

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Statistics

Date

Feb 20, 2024

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docx

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Uploaded by DukeSnakeMaster992

Lab 4 STAT 281 Name: - Section:- Group Round to 2 decimal places as necessary. 1. Using the “STAT 281 Survey Spring 20 Cleaned” Data Set, plot height and weight as a scatter plot in Excel (where x = height). Add in the line of best fit to the graph. A. Is there a positive or negative correlation? Positive correlation B. Are any points either outliers or potential influential observations? Yes, there is ONE point. (5.3) C. What is the correlation coefficient r for the graph? Is there a weak, moderate or strong relationship for r? WEAK 2. Now re-graph it without the outliers or influential observations you recognized above. A. Include screenshot or sketch below.

B. What is the correlation coefficient r for the graph without these points? Is there a weak, moderate or strong relationship for r ? Moderate C. What is r 2 what information does that tell us? So, r 2 is 0.3502 which tells us the proportions of variance which can be know by independent variable. 3. Continue with the data from #2. A. Find the equation of the line of best fit: Y = 5.3563x – 199.48 B. What is the y -intercept for our line of best fit? What information does it give us? Y-Intercept: -199.48 It tells us that height is o and weight are -199.48 C. What is the slope and what information does it give us? Slope: 5.3563 Interpretation: This suggests that for each additional inch in height, the model predicts an average increase of 5.3563 pounds in weight. D. How much would you predict someone who is 75 inches tall to weigh according to the line of best fit? Show work. Round your answer to the nearest tenth of a pound. Predicted Weight: Approximately 202.2425 pounds. E. Would it be appropriate to make a prediction about someone that is 50 inches tall? Why or why not? Likely inappropriate, as the prediction would go outside the range of the data, making it unreliable. F. Change the number of decimal places that show in Excel for your line of best fit.

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