Now as you can see, we have three prediction rules,
and the first question is what are the three predictions
that they give for this week.
So, prediction 1, attendance last week,
well we can see that that attendance last week was 40,
and the prediction is 40,
so all of these actually have the correct answer for prediction 1.
The second one is 100 minus attendance last week - 60.
100 - 40
And then 20 plus attendance last week, 20 + 40 is 60
so that shows us that answer A is the correct one.
Now notice that none of these strategies
used this data of the attendance two weeks ago.
They don't have to, even though it is available to them,
they don't have to use it.
Now let's go to question 2.
This asks what did the three prediction rules say last week.
So last week, the attendance we see was 40 but before we even knew that,
we wanted to know what the prediction rules predict.
So prediction 1 says attendance last week,well that would have been 70
because it was the week before we're predicting.
So prediction 1 is 70
prediction 2 is 100 minus attendance last week. 100 - 70 is 30.
And prediction 3 is 20 plus attendance last week. 20 + 70 is 90.
So the correct answer is C.
So now we want to know which strategy is the current best.
And that was defined as the one that was closest to predicting correctly last week.
Last week the real answer was 40, and the closest prediction to 40,
well, 30 is closer to 40 than 90 or 70,
so prediction 2 gives us the best prediction,
and that's the one we're going to use this week.
Prediction 2 for this week was 60.
Well that's just at the threshold
and we said the rule was
if you are at the threshold, or below, then you go.
So our answer is to go.