Introduction to Probability · free preview

The Moment Generating Function

Packaging all moments into one function, reading moments off derivatives, and recognizing distributions by their MGFs.

1. One function, every moment

One function, every moment

2. A catalog of MGFs

A catalog of MGFs

3. Existence, uniqueness, and what MGFs are for

Existence, uniqueness, and what MGFs are for

4. What the MGF stores

The r-th derivative of the MGF evaluated at t = 0 equals what?

5. Identifying by table

A random variable has MGF equal to e raised to the quantity 2 times e to the t, minus 2. Which distribution is it?

6. Bernoulli MGF moment

The Bernoulli(p) MGF is 1 - p + p e^t. Its first derivative at t = 0 is e^0 = 1 times p, plus zero. For p = 0.3, what is the mean? Enter a decimal like 0.3.

7. Exponential mean from MGF

The Expo(lambda) MGF is lambda over (lambda minus t). For lambda = 4, M'(0) = lambda squared over lambda squared, or compute directly: what is the mean? Enter a decimal like 0.25.

8. Uniform MGF check

The Uniform(0,1) MGF is (e^t minus 1) over t. Near t = 0 it limits to 1. Its series begins 1 + t/2 + t squared over 6. What is E(X)? Enter a decimal like 0.5.

9. In your own words

In your own words, state the most important definition, theorem or method of this lesson and explain what it says.

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