Using data to predict an event that has yet to occur is statistical prediction.
Inferring the value of a population quantity such as the average income of a country or the proportion of eligible voters who say they will vote ‘yes’ is statistical inference.
Prediction and inference answer different types of statistical questions.
The following are examples of predictions because the events have not occurred at the time of writing this post.
The probability that the Miami Heat will win the 2012 NBA playoffs is ____.
The probability that Barack Obama will win the 2012 Presidential election is ____.
The following are examples of inferences because the questions involve estimating a population value.
The proportion of NBA fans that currently believe the Miami Heat will win the 2012 playoffs is ____.
The proportion of eligible voters that currently state they will vote for Barack Obama in the 2012 Presidential election is ____.