Chapter 13 Linear Regression and Correlation True/False 1. If a scatter diagram shows very little scatter about a straight line drawn through the plots‚ it indicates a rather weak correlation. Answer: False Difficulty: Easy Goal: 1 2. A scatter diagram is a chart that portrays the correlation between a dependent variable and an independent variable. Answer: True Difficulty: Easy Goal: 1 AACSB: AS 3. An economist is interested in predicting
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| 70 | 29 | E | 22 | 6 | F | 27 | 15 | G | 28 | 17 | H | 47 | 20 | I | 14 | 12 | J | 68 | 29 | | | | | | | a) draw a scatter diagram of number of sales calls and number of units sold b) Estimate a simple linear regression model to explain the relationship between number of sales calls and number of units sold y=2.139x-1.760 Number of units sold=2.139Number of units sold-1.760 c) Calculate and interpret the coefficient of correlation r=0.853=0.9236 (There
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Important EXERCISE 27 SIMPLE LINEAR REGRESSION STATISTICAL TECHNIQUE IN REVIEW Linear regression provides a means to estimate or predict the value of a dependent variable based on the value of one or more independent variables. The regression equation is a mathematical expression of a causal proposition emerging from a theoretical framework. The linkage between the theoretical statement and the equation is made prior to data collection and analysis. Linear regression is a statistical method of estimating
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lagged drivers – Use correlation to pick a lagged driver – Build a linear forecast model using regression‚ perform DW test on residuals – Repeat if residuals do not pass DW test • Forecast revenues and generate 95% prediction intervals for 2009 and 2010 6 Revitalizing Dell: Bright forecast 7 Revitalizing Dell: Harsh reality 8 Revitalizing Dell: What did our model miss? • HP sales data not “clean” (starts to include Compaq since 2002) • Ratings lack variation (could have used Dell’s
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Limitations: Regression analysis is a commonly used tool for companies to make predictions based on certain variables. Even though it is very common there are still limitations that arise when producing the regression‚ which can skew the results. The Number of Variables: The first limitation that we noticed in our regression model is the number of variables that we used. The more companies that you have to compare the greater the chance your model will be significant. We have found that
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Poisson Regression This page shows an example of poisson regression analysis with footnotes explaining the output. The data collected were academic information on 316 students. The response variable is days absent during the school year (daysabs)‚ from which we explore its relationship with math standardized tests score (mathnce)‚ language standardized tests score (langnce) and gender . As assumed for a Poisson model our response variable is a count variable and each subject has the same length
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Multiple regression‚ a time-honored technique going back to Pearson’s 1908 use of it‚ is employed to account for (predict) the variance in an interval dependent‚ based on linear combinations of interval‚ dichotomous‚ or dummy independent variables. Multiple regression can establish that a set of independent variables explains a proportion of the variance in a dependent variable at a significant level (through a significance test of R2)‚ and can establish the relative predictive importance
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P(x) = 300 — 4x. The cost function is c(x) = 500 + 28x where x is the number of units produced. Find x so that the profit is maximum. Question: 1) Find the value of x. 2) In using regression analysis for making predictions what are the assumptions involved. 3) What is a simple linear regression model? 4) What is a scatter diagram method? CASE STUDY : 3 Mr Sehwag invests Rs 2000 every year with a company‚ which pays interest at 10% p.a. He allows his deposit
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I loved my brother Allie so much‚ that’s why I kept his baseball mitt. I couldn’t stand thinking about that I’ll never see him again! I guess because of that the mitt is so damn valuable to me. Well‚ and it really was a huge part of Allie‚ that’s why it makes me feel good; because only I have it. Allie’s baseball mitt is a left-handed baseball mitt. The whole mitt is a light brown color because it is very worn. Yeah‚ you can even smell the smell of old leather and the dirt. If you’ll be looking
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Role Set Analysis is a method that helps people to think through what is expected of them and they could clash and cause other issues. This method helps managers to check whether or not they are using time effectively. It compares existing procedures with current priorities. By using this method it can help to show what the end objective of the job being analyzed should be. There are many advantages of using the Role Set Analysis. It is easy to apply or update‚ it assists managers to ask certain
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