Mr Dotson wants to know if The neighbors on his street would be interested in a community watch he surveyed every fourth household on the street and concluded that 70% would be interested

It is valid because it is a systematic random sample.

Step-by-step explanation:

with example?

In Systematic random sampling it involves the random sampling method which also involves selecting of samples on the premix/basis on a system of intervals in a numbered population. It is also a way/means samples selection at a particular preset interval.

It can be broken down into steps examples

1.calculate and quickly fix the sampling interval. (The number of elements in the population divided by the number of elements needed for the sample.)

2 Take a random starting point between 1 and the sampling interval.

3. repeat the sampling interval to choose subsequent elements.