10 Generalized Linear Regression
In the problems of this section
$$x^T \beta = \beta_0 + \sum_{i=1}^p \beta_i x_i$$
Problem 10.1.
€~ Logistic(0, 1), iff its probability density function (pdf) is
$$\sigma'(x) = \frac{d}{dx}\sigma(x) = \frac{e^{-x}}{(1+e^{-x})^2}$$
a) Verify the primitive function
$$\int \sigma'(t)dt = \frac{1}{1+e^{-x}} + C$$
and determine C. Set
$$\sigma(x) := \frac{1}{1+e^{-x}}$$
b) Show that
$$P(-\epsilon \leq x) = P(\epsilon \leq x).$$
You may use (131) even if you have failed to show it.
c) Define
$$Y^* = x^T \beta + \epsilon$$
and construct
$$Y = \begin{cases}
1 & \text{if } Y^* > 0 \\
0 & \text{otherwise}.
\end{cases}$$
Verify that
$$P(Y= 1 | x) = \sigma (x^T \beta).$$
You may use (132) even if you have failed to show it.
(133)
d) The r.v. Y in this assignment is a special case of generalized linear regression (GLM). The
way to construct a GLM goes via a link function. Present and justify the link function in
this assignment.