Model Trendline Linear 3Factor Excel by Milo Schield Member: International Statistical Institute US Rep: International Statistical Literacy Project Director, W. M. Keck Statistical Literacy Project Slides at: /Model-Trendline-Linear-3Factor-Excel2013-6up.pdf Model using Trendline Linear 3Factor in Excel 2013

Model Trendline Linear 3Factor Excel Goal: Summarize association before/after control for Gender 1.Generate six XY charts as shown. No writing. 2.Show linear trendline, regression and R 2 as shown. Use XL1 (Pulse.xls) data set. Subjects are college students. Pulse1 is their resting pulse. For details on using Excel Chart Trendline to build a model, see Model-Trendline-Linear-Excel2013-6up.pdf

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Model Trendline Linear 3Factor Excel Need separate series for Men and for Women Step 1. Copy data to a new sheet. Sort entire dataset by MALE Step 2. Copy sorted data from A:H to J:Q. Change headings to distinguish M vs. F. Step 3. Delete guys from gals series (Male=0); delete gals from guys series (Male=1). Step 4. Use separated cols for graphs 5 and 6.

Model Trendline Linear 3Factor Excel Move data into separate series (separate columns) by Gender Women: Min(Weight-F) = 95# Max(Weight-F) = 150# Min(Weight-M) = 123# Max(Weight-M) = 215# Men:

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Model Trendline Linear 3Factor Excel Results in words #1 As height increases by 1 inch, weight increases by 5.1 pounds (R-squared = 62%) rest pulse decreases by 0.64 bpm (R-squared = 5%) #3W For women, as height increases by 1 inch, weight increases by 2.6 pounds (R-squared = 24%) rest pulse decreases by 0.48 bpm (R-squared = 1%) #3M For men, as height increases by 1 inch, weight increases by 4.4 pounds (R-squared = 36%) rest pulse INCREASES by 0.21 bpm (R 2 = 0.3%)

Model Trendline Linear 3Factor Excel Conclusion Difference in gender explains part of the association between height and related variables such as weight and resting pulse. Failure to take into account gender can result in: associations that are spurious. associations that reverse associations that increase or decrease. Moral: What you take into account matters!