Problems tagged with "histogram estimators"

Problem #34

Tags: histogram estimators

Consider the data set of ten points shown below:

Suppose this data is used to build a histogram density estimator, \(f\), with bins: \([0,2), [2, 6), [6, 10)\). Note that the bins are not evenly sized.

Part 1)

What is \(f(1.5)\)?

Part 2)

What is \(f(7)\)?

Problem #35

Tags: histogram estimators

Consider this data set of points \(x\) from two classes \(Y = 1\) and \(Y = 0\).

Suppose a histogram estimator with bins \([0,1)\), \([1, 2)\), \([2, 3)\) is used to estimate the densities \(p_1(x \given Y = 1)\) and \(p_0(x \given Y = 0)\), and these estimates are used in the Bayes classifier to make a prediction.

What will be the predicted class of a new point, \(x = 2.2\)?

Solution

Class 0.

Problem #36

Tags: density estimation, histogram estimators

Suppose a density estimate \(f : \mathbb R^3 \to\mathbb R^1\) is made using histogram estimators with bins having a length of 2 units, a width of 3 units, and a height of 1 unit.

What is the largest value that \(f(\vec x)\) can possibly have?

Problem #48

Tags: histogram estimators

Consider this data set of points \(x\) from two classes \(Y = 1\) and \(Y = 0\).

Suppose a histogram estimator with bins \([0,2)\), \([2, 4)\), \([4, 6)\) is used to estimate the densities \(p_1(x \given Y = 1)\) and \(p_0(x \given Y = 0)\).

What will be the predicted class-conditional density for class 0 at a new point, \(x = 2.2\)? That is, what is the estimated \(p_0(2.2 \given Y = 0)\)?

Solution

1/6.

When estimating the conditional density, we look only at the six points in class zero. Two of these fall into the bin, and the bin width is 2, so the estimated density is:

\[\frac{2}{6 \times 2} = \frac{1}{6}. \]

Problem #49

Tags: histogram estimators

Suppose \(\mathcal D\) is a data set of 100 points. Suppose a density estimate \(f : \mathbb R^3 \to\mathbb R^1\) is constructed from \(\mathcal D\) using histogram estimators with bins having a length of 2 units, a width of 2 units, and a height of 2 units.

The density estimate within a particular bin of the histogram is 0.2. How many data points from \(\mathcal D\) fall within that histogram bin?