Exam 1

1. Metainformation

   Tag	Value
   file	Inferential_Statistics_vufsw-equation-1026-en_vufsw-equation-1026-en
   name	vufsw-equation-1026-en
   section	inferential statistics/regression/equation
   type	schoice
   solution	TRUE, FALSE, FALSE, FALSE
   Type	interpreting output
   Program	NA
   Language	English
   Level	statistical literacy

   Question

   If you were researching the effect of hours of training (predictor) and attitude (moderator) on the performance of a specific skill (e.g. the number of goals scored: performance) and the regression results give you the following regression equation, which of the following statements is incorrect?

   All the variables in this regression are mean-centred.

   performance = 1.23^* + 0.112 × attitude + 0.531^* × hours + 0.167^* × attitude × hours

   * indicates a statistically significant effect

   
   
   1. TRUE: The effect of hours training on the performance of a specific skill is lower for higher scores of attitude than for lower scores of attitude.
   2. FALSE: The effect of hours training on the performance of a specific skill is higher for higher scores of attitude than for lower scores of attitude.
   3. FALSE: The mean score in performance in a specific skill equals 1.23 if hours of training and attitude equal its mean values.
   4. FALSE: If the variable hours of training equal its mean, then an increase of attitude by 1 unit results in a mean increase of performance by 0.112 units.
   
   

   Solution

   The correct answer is the option "The effect of hours training on the performance of a specific skill is lower for higher scores of attitude than for lower scores of attitude". This is correct because the statement is incorrect! The regression equation shows that the interaction effect (0.167) is positive and not negative as the statement suggests. This means that the effect of hours on performance increases with attitude.

   The option “The effect of hours training on the performance of a specific skill is higher for higher scores of attitude than for lower scores of attitude” is incorrect because the statement is correct! The regression equation shows that the interaction effect (0.167) is positive. This means that the effect of hours on performance increases with attitude.

   The option “The mean score in performance in a specific skill equals 1.23 if hours of training and attitude equal its mean values” is incorrect because the statement is correct! Both attitude and hours are mean-centred, so when these variables take their mean value, they should be replaced with 0 in the regression equation. This means that in that case, performance would equal the constant = 1.23.
   performance = 1.23^* + 0.112 × attitude + 0.531^* × hours + 0.167^* × attitude × hours = 1.23 + 0.112 × 0 + 0.531^* × 0 + 0.167^* × 0 × 0 = 1.23

   The option “If the variable hours of training equal its mean, then an increase of attitude by 1 unit results in a mean increase of performance by 0.112 units” is incorrect because the statement is correct! Hours training is mean-centred, so when this variable takes its mean value, it should be replaced with 0 in the regression equation. In this case, the effect of attitude on performance is 0.112.

   performance = 1.23^* + 0.112 × attitude + 0.531^* × hours + 0.167^* × attitude × hours = 1.23 + 0.112 × attitude + 0.531^* × 0 + 0.167^* × attitude × 0 = 1.23 + 0.112 × *attitud**e*

   
   
   1. True
   2. False
   3. False
   4. False