Statistical Methods DY0-001 Practice Questions (Page 3)

Questions 11–15

1. 11foundation · easy

   What does R-squared measure in a regression model?

   • AThe correlation between the independent variables
   • BThe proportion of variance in the dependent variable explained by the independent variables
   • CThe slope of the regression line
   • DThe significance of the regression coefficients
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2. 12foundation · easy

   Why is adjusted R-squared often preferred over R-squared when comparing regression models with different numbers of predictors?

   • AIt is easier to calculate than R-squared
   • BIt always increases with more predictors
   • CIt measures the correlation between predictors
   • DIt penalizes the addition of unnecessary predictors
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4. 13application · medium

   An e-commerce company wants to know if customer satisfaction (satisfied vs. not satisfied) is related to the shipping method used (standard, expedited, or overnight). They collect data from 500 recent orders and create a contingency table. Which test should they use to determine if there is a statistically significant association between these two categorical variables?

   • AOne-way ANOVA
   • BPaired t-test
   • CIndependent t-test
   • DChi-squared test of independence
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5. 14application · medium

   A pharmaceutical company is testing a new blood pressure medication. They measure systolic blood pressure for 30 patients before treatment and again after 8 weeks of treatment. The mean difference is -8 mmHg with a standard deviation of 12 mmHg. The data are approximately normally distributed. Which statistical test is most appropriate to determine whether the medication significantly reduced blood pressure?

   • AOne-way ANOVA
   • BIndependent two-sample t-test
   • CChi-squared test
   • DPaired t-test
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6. 15foundation · easy

   What is the primary purpose of the Akaike Information Criterion (AIC) in model selection?

   • ATo measure the accuracy of a classification model
   • BTo test the significance of individual predictors
   • CTo compare the fit of different models while penalizing for the number of parameters
   • DTo determine the correlation between variables
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