a 13) The following regression analysis predicted force, which was the grip strength a person maintained on a handle in

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A 13 The Following Regression Analysis Predicted Force Which Was The Grip Strength A Person Maintained On A Handle In 1 (221 KiB) Viewed 23 times

A 13 The Following Regression Analysis Predicted Force Which Was The Grip Strength A Person Maintained On A Handle In 2 (116.35 KiB) Viewed 23 times

a 13) The following regression analysis predicted force, which was the grip strength a person maintained on a handle in a lab task. People were asked to maintain a certain grip strength, measured as force for a period of time. Initially a display showed them how much force they were using. Then there were two conditions – if feedback=0, the display number disappeared and the person had to judge for themselves if they were maintaining the right force. If feedback = 1, they continued to see on the display how hard they were gripping. The goal of the study is to see how well people can maintain a specific grip in the absence of feedback telling them how hard they are gripping. The researchers also took self-report measures of perseverance (range 1 to 9, where 9 is high). The wais score (range 1-20) was a measure of cognitive ability. Their first model predicted force using feedback, perseverance, and wais. Call: lm (formula = force ~ examlbb) feedback + perseverance + wais, data = Coefficients: Estimate Std. Error t value Pr(>[t]) (Intercept) 185.7811 13.1715 14.105 < 2e-16 *** feedback 38.9020 5.9006 6.593 5.08e-09 *** perseverance 3.2358 1.3046 2.480 0.0153 * wais 0.2809 1.0108 0.278 0.7818 Signif. codes: 0 *** 0.001 "** 0.01 *' 0.05 '.' 0.1'' 1 Wwwwww Residual standard error: 26.39 on 76 degrees of freedom Multiple R-squared: 0.3986, Adjusted R-squared: 0.3749 F-statistic: 16.79 on 3 and 76 DF, p-value: 1.832e-08

Ka) Interpret the coefficient for perseverance. (2 points) (6) What is the result of a test of the null hypothesis that the slope for wais is 0? (2 points). (c) Participants were randomly assigned to be in either of the two feedback conditions. Give an interpretation of the slope for feedback. Explain how "strong" you can be with your language, and why. (4 points). d) The total sum of squares (SSTO) is 87999, and the sum of squares for error (SSE) is 52922. Show how to calculate the overall F-statistic found at the bottom of the model summary. (3 points) e) Find the predicted grip force for someone in the no feedback condition (feedback = 0) and with perseverance = 8 and wais = 8. You may round a bit as you calculate. (2 points). f) The researcher asks for_vif(modl) and gets the following: feedback perseverance 1.00000 1.05533 wais 1.05533 Is collinearity an issue for this model? (2 points).