Exercise

# Prediction vs. inference

The figure to the right contrasts two groups of simulated values for the reaction test game.

The top histogram displays simulated values of the mean reaction time `M`

(from John's normal posterior density) and the bottom histogram graphs simulated values of the predictive density for the test score `y`

.

Which statement best summarizes the difference between these two sets of simulated values?

Instructions

**50 XP**

##### Possible Answers

- The two histograms have similar averages and spreads.
- The two histograms have similar averages but the histogram of the predictive density of
`y`

has much larger spread. - The two histograms have similar averages but the histogram of the posterior density for
`M`

has much larger spread. - The averages and spreads of the two histograms are both significantly different.