9. PLAN DE RECURSOS HUMANOS
10.5 Presupuesto de egresos a precios constantes
Surprise behaves a lot like the logarithm of probability. The advantage of thinking entirely in terms of surprise affects is that this process can become very instinctive and take on the order of a second or so.
This is the kind of 1-second Bayes discussed in the outline. Here's what the steps look like when combined, for the restaurant example above:
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Without the instructions written in, the thought process looks a bit simpler:
Practicing using your Surprisometer to construct a prior as a surprisal difference:
In each of the following examples, write down a short name for the hypothesis being considered and an alternative, as in Drill #0. Your prior is that you would have expected before seeing the evidence, and what odds you'd give to that expectation You may use the techniques listed above to help you decide your prior.
1. Example: The restaurant can’t be good, or it would be more crowded.
(This means your Surprisometer thinks good restaurants are more common than bad ones.)
2. A volunteer from the campaign visited me; that’s evidence that they’re well-organized.
3. I’m very good at this subject, so my low test score must mean there was a Scantron error.
4. My car keys are missing, because my kids hid them.
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5. I believe she’s telling the truth, because she didn’t look away when she told me.
6. My friend hasn’t mentioned the fight again, so he’s not angry.
7. This candidate graduated from an Ivy League school; she’s probably qualified for the job.
How to use your Surprisometer to judge Strength of Evidence as a surprisal difference
1 Imagine you knew that your hypothesis was true (you like the book). Would it be surprising to find out that you saw the evidence that you observed (that your friend liked it, too)?
2 Imagine you knew that your hypothesis was false (you don’t like the book). Would it be surprising to find out that you saw the evidence that you observed (that your friend liked it, too)?
3 Compare how far out on your surprise-o-meter each of these hypotheticals fall.
a If there’s a large disparity, the evidence is stronger.
b If the gap is small, the evidence is weaker.
4 It could be that you’d be very surprised to see this evidence in either case. Whether or not intelligent aliens exist, you’d be surprised to be personally contacted. But the gap is large, even though both scenarios are unexpected.
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Practice using your Surprisometer to judge Strength of Evidence as a surprisal difference:
Imagine you knew the hypothesis was true. – How surprising would it be to have observed this
evidence? How surprised would you be to see it if the hypothesis were definitely false? Compare your surprise gap to judge whether this evidence is strong, moderate, or weak. When you’ve rated them all, check if propositions in the same category feel similar, or if you want to subdivide your ratings.
1. The restaurant can’t be good, or it would be more crowded.
(This means you are more surprised when a good restaurant turns our to be not crowded than when a bad restaurant turns out to be more crowded.)
2. [A specific friend] enjoyed this book, therefore I will, too.
3. A volunteer from the campaign visited me: that’s evidence that they’re well-organized.
4. I’m very good at this subject, so my low test score must mean there was a Scantron error.
5. My car keys are missing, because my kids hid them.
6. I believe she’s telling the truth, because she didn’t look away when she told me.
7. My friend hasn’t mentioned the fight again, so he’s not angry.
8. This candidate graduated from an Ivy League school; she’s probably qualified for the job.
9. This candidate stumbled over a question in the interview; she’s probably not qualified.
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Practice using your Surprisometer to form a Posterior as a surprisal difference
Imagine you knew the hypothesis was true. – How surprising would it be to have observed this
evidence? How surprised would you be to see it if the hypothesis were definitely false? Compare your surprise gap to judge whether this evidence is strong, moderate, or weak. When you’ve rated them all, check if propositions in the same category feel similar, or if you want to subdivide your ratings.
1. Example: This restaurant can’t be good, or it would be more crowded.
2. [A specific friend] enjoyed this book, therefore I will, too.
3. A volunteer from the campaign visited me: that’s evidence that they’re well-organized.
4. I’m very good at this subject, so my low test score must mean there was a Scantron error.
5. My car keys are missing, because my kids hid them.
6. I believe she’s telling the truth, because she didn’t look away when she told me.
7. My friend hasn’t mentioned the fight again, so he’s not angry.
8. This candidate graduated from an Ivy League school; she’s probably qualified for the job.
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Practice choosing what evidence to seek
Pick 3 of the examples from the previous list. Try to come up with a different piece of evidence that would be stronger evidence for the given hypothesis. Use either likelihood ratios or surprisal differences to compare your assessments of strength of evidence.
Pick 3 of the examples from the previous list. Try to come up with a different piece of evidence that would be weaker evidence for the given hypothesis. Use either the qualitative or quantitative exercises to compare your assessments of strength of evidence.