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What is the line of means?

Short Answer

Expert verified

The equation y= β0+ β1x is referred to as the line of means in the Probabilistic model.

Step by step solution

01

Introduction.

A probabilistic model has both a deterministic and a random error component. For example, suppose we anticipate that sales y are related to advertising spend x by

y = 15x + Random error

General Form of Probabilistic Models:

y = Deterministic component + Ramdom error,

Where, y is the variable of interest we always assume that the mean value of the random mistake is 0. This is comparable to assuming that the mean value of y, E(y), equals the model's deterministic component; that is,

E(y) = Deterministic component.

02

Brief explanation to the line of means.

We know that a basic linear regression equation has the form, where y= β0+ β1x is the dependent variable,x is the independent variable, β0is the intercept, β1is the slope ε and is an error random variable with mean 0 and variance of . The probabilistic model will then bey= β0+ β1x. If we consider E(y), we may determine that

E(y)= β0+ β1x.

Every y value is normally distributed with mean values based on x for each value of x. When we plot this E(y) with x, we obtain a straight line with all mean lying on it; this line is known as the line means.

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Most popular questions from this chapter

Question: The speed with which consumers decide to purchase a product was investigated in the Journal of Consumer Research (August 2011). The researchers theorized that consumers with last names that begin with letters later in the alphabet will tend to acquire items faster than those whose last names begin with letters earlier in the alphabet—called the last name effect. MBA students were offered free tickets to an event for which there was a limitedsupply of tickets. The first letter of the last name of those who responded to an email offer in time to receive the tickets was noted as well as the response time (measured in minutes). The researchers compared the response times for two groups of MBA students: (1) those with last names beginning with one of the first nine letters of the alphabet and (2) those with last names beginning with one of the last nine letters of the alphabet. Summary statistics for the two groups are provided in the table.

First 9

Letters: A–I

Last 9

Letters: R–Z

Sample size

25

25

Mean response time (minutes)

25.08

19.38

Standard deviation (minutes)

10.41

7.12

Source: Based on K. A. Carlson and J. M. Conrad, “The Last Name Effect: How Last Name Influences Acquisition Timing,” Journal of Consumer Research, Vol. 38, No. 2, August 2011.

a. Construct a 95% confidence interval for the difference between the true mean response times for MBA students in the two groups.

b. Based on the interval, part a, which group has the shorter mean response time? Does this result support the researchers’ last name effect theory? Explain.

Traffic sign maintenance. Refer to the Journal of Transportation Engineering (June 2013) study of traffic sign maintenance in North Carolina, Exercise 8.54 (p. 489). Recall that the proportion of signs on NCDOT-maintained roads that fail minimum requirements was compared to the corresponding proportion for signs on county-owned roads. How many signs should be sampled from each maintainer to estimate the difference between the proportions to within .03 using a 90% confidence interval? Assume the same number of signs will be sampled from NCDOT-maintained roads and county-owned roads

Given that xis a hypergeometric random variable, computep(x)for each of the following cases:

a. N= 8, n= 5, r= 3, x= 2

b. N= 6, n= 2, r= 2, x= 2

c. N= 5, n= 4, r= 4, x= 3

Producer willingness to supply biomass. The conversion of biomass to energy is critical for producing transportation fuels. How willing are producers to supply biomass products such as cereal straw, corn stover, and surplus hay? Economists surveyed producers in both mid-Missouri and southern Illinois (Biomass and Energy, Vol. 36, 2012). Independent samples of 431 Missouri producers and 508 Illinois producers participated in the survey. Each producer was asked to give the maximum proportion of hay produced that they would be willing to sell to the biomass market. Summary statistics for the two groups of producers are listed in the table. Does the mean amount of surplus that hay producers are willing to sell to the biomass market differ for the two areas, Missouri and Illinois? Use a = .05 to make the comparison.

Buy-side vs. sell-side analysts' earnings forecasts. Refer to the Financial Analysts Journal (Jul. /Aug. 2008) study of financial analysts' forecast earnings, Exercise 2.86 (p. 112). Recall that data were collected from 3,526 buy-side analysts and 58,562forecasts made by sell-side analysts, and the relative absolute forecast error was determined for each. The mean and standard deviation of forecast errors for both types of analysts are given in the table.

a. Construct a 95% confidence interval for the difference between the mean forecast error of buy-side analysts and the mean forecast error of sell-side analysts.

b. Based on the interval, part a, which type of analysis has the greater mean forecast error? Explain.

c. What assumptions about the underlying populations of forecast errors (if any) are necessary for the validity of the inference, part b?

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