Question: Tilting in online poker. In poker, making bad decisions due to negative emotions is known as tilting. A study in the Journal of Gambling Studies (March, 2014) investigated the factors that affect the severity of tilting for online poker players. A survey of 214 online poker players produced data on the dependent variable, severity of tilting (y), measured on a 30-point scale (where higher values indicate a higher severity of tilting). Two independent variables measured were poker experience (x1, measured on a 30-point scale) and perceived effect of experience on tilting (x2, measured on a 28-point scale). The researchers fit the interaction model, . The results are shown below (p-values in parentheses).

  1. Evaluate the overall adequacy of the model using α = .01.

b. The researchers hypothesize that the rate of change of severity of tilting (y) with perceived effect of experience on tilting (x2) depends on poker experience (x1). Do you agree? Test using α = .01.

Short Answer

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Answer

  1. At 95% confidence interval, it can be concluded that at least one of the parametersβ1,β2,orβ3isnonzero.

b, At 95% confidence interval it is concluded that β3=0 Hence it can be concluded with enough evidence that x1and x2do not interact in the model.

Step by step solution

01

Overall adequacy of the model

To test the overall adequacy of the model, F-test is conducted

H0:β1=β2=β3=0Ha:Atleastoneoftheparametersβ1,β2,orβ3isnonzero

Here, F test statistic = SSEn-k+1=31.98

Value of F0.05,213,213 is 2.605

H0is rejected if F static >F0.05,213,213 for α=0.05,Since F >F0.05,213,213

Sufficient evidence to reject H0at 95% confidence interval

Thus,atleastoneoftheparametersβ1,β2,orβ3isnonzero

02

 Step 2: Overall adequacy of the model

H0:β3=0H0:β30

Here, t-test statistic = β^ssβ^s=-5.61

Value oft0.05,213 is 1.96

H0is rejected if t static > t0.05,24,24 .α=0.05 since t < t0.05,24,24

Not sufficient evidence to reject H0at 95% confidence interval

Therefore, β3=0

Hence it can be concluded with enough evidence that x1 and x2 donot interact in the model

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Most popular questions from this chapter

Question: Chemical plant contamination. Refer to Exercise 12.18 (p. 725) and the U.S. Army Corps of Engineers study. You fit the first-order model,E(Y)=β0+β1x1+β2x2+β3x3 , to the data, where y = DDT level (parts per million),X1= number of miles upstream,X2= length (centimeters), andX3= weight (grams). Use the Excel/XLSTAT printout below to predict, with 90% confidence, the DDT level of a fish caught 300 miles upstream with a length of 40 centimeters and a weight of 1,000 grams. Interpret the result.

It is desired to relate E(y) to a quantitative variable x1and a qualitative variable at three levels.

  1. Write a first-order model.

  2. Write a model that will graph as three different second- order curves—one for each level of the qualitative variable.

Question:If the analysis of variance F-test leads to the conclusion that at least one of the model parameters is nonzero, can you conclude that the model is the best predictor for the dependent variable ? Can you conclude that all of the terms in the model are important for predicting ? What is the appropriate conclusion?

Suppose you fit the quadratic model E(y)=β0+β1x+β2x2to a set of n = 20 data points and found R2=0.91, SSyy=29.94, and SSE = 2.63.

a. Is there sufficient evidence to indicate that the model contributes information for predicting y? Test using a = .05.

b. What null and alternative hypotheses would you test to determine whether upward curvature exists?

c. What null and alternative hypotheses would you test to determine whether downward curvature exists?

Question: Refer to Exercise 12.82.

a. Write a complete second-order model that relates E(y) to the quantitative variable.

b. Add the main effect terms for the qualitative variable (at three levels) to the model of part a.

c. Add terms to the model of part b to allow for interaction between the quantitative and qualitative independent variables.

d. Under what circumstances will the response curves of the model have the same shape but different y-intercepts?

e. Under what circumstances will the response curves of the model be parallel lines?

f. Under what circumstances will the response curves of the model be identical?

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