1. Simple Random Sampling
Lecture 6
Section 2.5
Mon, Sep 6, 2004

2. Simple Random Sample
Simple Random Sample of size n – A sample of size n chosen in such a way that all possible samples of size n have the same chance of being selected.

3. Selecting a Simple Random Sample
Given a population of size N,
Number the members from 1 to N.
Use a random number generator (such as on a calculator) to generate n random integers from 1 to N.
The sampling may be done with or without replacement.
If the sampling is done without replacement, then repetitions should be discarded.

4. TI-83 – Selecting a Sample
Suppose that the population size is N = 100.
Press MATH.
Use arrow keys to highlight PRB menu.
Press 5 to select randInt (item #5).
Enter randInt(1, 100) and press ENTER.
A random number appears.
Press ENTER repeatedly for more random numbers.

5. TI-83 – Setting the Seed Enter the desired seed, say, 33. Press STO.
Press MATH, highlight PRB, select rand (item #1).
Press ENTER. The seed is set to 33.

6. Example
Example 2.14, p. 88 – Simple Random Sampling of Forest Sites.

7. Let’s Do It! Let’s do it! 2.4 – A Simple Random Sample of Companies.
Let’s do it! 2.5 – Simple Random Sampling.
Divide the class into two groups.
Change “proportion of women” to “proportion of freshmen.”