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How well do professional golfers putt from various distances to the hole? The scatterplot shows various distances to the hole (in feet) and the per cent of putts made at each distance for a sample of golfers.

The graphs show the results of two different transformations of the data. The first graph plots the natural logarithm of per cent made against distance. The second graph plots the natural logarithm of per cent made against the natural logarithm of distance.

a. Based on the scatterplots, would an exponential model or a power model provide a better description of the relationship between distance and per cent made? Justify your answer.

b. Here is computer output from a linear regression analysis of ln(per cent made) and distance. Give the equation of the least-squares regression line. Be sure to define any variables you use.

c. Use your model from part (b) to predict the per cent made for putts of 21 feet.

d. Here is a residual plot for the linear regression in part (b). Do you expect your prediction in part (c) to be too large, too small, or about right? Justify your answer.

Short Answer

Expert verified

(a) The linear model between In (per cent created) and distance is correct, the exponential model between per cent made and distance is also correct.

(b) lny=4.6649-0.1091x

(c) The expected percent is10.7381.

(d) The prediction was too low.

Step by step solution

01

Part (a) Step 1: Given information

The given data is

02

Part (a) Step 2: Explanation

From the above-given data

Because the scatter plot between ln(per cent made) and the distance does not have considerable curvature, a linear model between the two variables of the scatter plot would be acceptable.

As a result, a linear model between In(per cent made) and distance is adequate. Expect ln(count) from time using a general linear model.

ln(percentmade)=a+b(distance)

Per cent maderole="math" localid="1654176006287" =eln(percent made)=ea+b(distance)

=eaeb(distance)

As a result, the model is associated with the per cent made=eaeb(distance) model, which is an exponential relationship between power and distance. While the linear model between In (per cent created) and distance is correct, the exponential model between per cent made and distance is also correct.

03

Part (b) Step 1: Given information

The given data is

04

Part (b) Step 2: Explanation

The equation for the least square regression line is

y^=b0+b1x

In the row "constant" and the column "Coef" of the computer output, the calculated constant b0is mentioned.

b0=4.6649

In the row "Distance" and the column "Coef" of the computer output, the calculated slope b1is mentioned.

b1=-0.1091

Then the value is

y^=b0+b1x

y^=4.6649-0.1091x

Therefore

lny=4.6649-0.1091x

Where x is the distance and y denotes the percentage achieved.

05

Part (c) Step 1: Given information

The given data is

06

Part (c) Step 2: Explanation

From part b

lny=4.6649-0.1091x

Where x is the distance and y denotes the percentage achieved.
lny=4.6649-0.1090(21)lny=2.3738

Take the exponential

y^=elnyy^=e2.3738

=10.7381

Then the per cent expected is10.7381.

07

Part (d) Step 1: Given information

The given data is

08

Part (d) Step 2: Explanation

It is observed that when a forecast for a distance of x=21feet is made, all dots roughly 20around are positive in the residual plot. As a result, the residual x=21is expected to be positive as well.

The difference between the projected y-value and the actual y-value is the residual. If a residual is positive, it signifies that the real y-value is higher than the projected y-value, implying that our prediction was too low.

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Most popular questions from this chapter

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