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Thinking Challanges- 13, 14, 18, 12

Thinking Challanges- 13, 14, 18, 12 - Thinking Challenge...

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Unformatted text preview: 12/16/11 Thinking Challenge The least squares method minimizes which of the following? Thinking Challenges Chapter 13 a) b) c) d) SSR(regression; explained variaFon) SSE(error; unexplained variaFon) SST(total) All of the above Parameter Point-EsFmate Thinking Challenge You're an economist for the county cooperaFve. You gather the following data: FerFlizer (lb.) Yield (lb.) 4 3.0 6 5.5 10 6.5 12 9.0 What is the relaFonship between ferFlizer and crop yield? SSxy = 26 SSxx = 40 ScaXer Diagram Crop Yield vs. FerFlizer Yield (lb.) 10 8 6 4 2 0 0 Fer4lizer (lb.) 5 10 15 1 12/16/11 Parameter EsFmaFon SoluFon InterpretaFon of Coefficients Slope (b1) Crop Yield (Y) is expected to increase by .65 lb. for each 1 lb. increase in FerFlizer (X). Y-Intercept (b0) Average Crop Yield (Y) is expected to be 0.8 lb. when no FerFlizer (X) is used. So, if you use 5 lbs. of ferFlizer you can expect an average crop yield of 4.05 lbs. per acre. Thinking Challenge The coefficient of determinaFon (r2) tells us a) b) c) d) That the coefficient of correlaFon (r) is larger than 1. Whether r has any significance. That we should not parFFon the total variaFon. The proporFon of total variaFon that is explained. Thinking Challenge If the correlaFon coefficient (r) = 1.00, then a) b) c) d) The Y-intercept (b0) must equal o. The explained variaFon equals the unexplained variaFon. There is no unexplained variaFon. There is no explained variaFon. 2 12/16/11 Chapter 14 Thinking Challenge If we can claim to account for .65 of the variance in Y scores by knowing a relaFonship, it means that: a) the data are 65% less variable than we thought. b) we are, on average, 65% more accurate at predicFng Y scores than if we did not know of the relaFonship. c) the data are 65% more variable that we thought them to be. d) we know where 65% of the variance comes from. Thinking Challenge In general, the greater the proporFon of variance accounted for, a) b) c) d) the more error there is in the data. the less accurately we can predict behavior. the more accurately we can predict behavior. the less important the relaFonship is to our ability to make predicFons. Chapter 18 3 12/16/11 Thinking Challenge If a control chart is used correctly and the necessary correcFve acFons are taken, as the control limits get _________, the potenFal quality of the product _____________. a) b) c) d) looser, increases Fghter, decreases Fghter, increases none of the above Thinking Challenge The p-chart is based on the ____________ distribuFon. a) b) c) d) normal F binomial exponenFal Chapter 12 Thinking Challenge As the differences between the observed frequency and expected frequency increase, a) b) c) d) The likelihood of rejecFng H0 also increases The likelihood of rejecFng H0 decreases The criFcal value for the chi-square increases The criFcal value for the chi-square decreases 4 12/16/11 Thinking Challenge The chi-square test for goodness-of-fit evaluates a) b) c) d) The relaFonship between two variables The mean differences between two or more treatments The shape or proporFons for a populaFon distribuFon None of the above Thinking Challenge The chi-square test for independence is used to test for a) A mean difference between two populaFons b) A difference between a sample distribuFon and a populaFon distribuFon c) A difference in variance between two populaFons d) A relaFonship between two variables 5 ...
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