suppose we want to take a poll of the attitudes of senior citizens in the state of washington describe how you would go about deterning this through
a. drawing a random sample
b. drawing a systematic sample
c. drawing a convience sample
(a) Random sample:We need a comprehensive list of all Washington State residents who fit our criteria (i.e. 55 years of age or older, 65+, whatever we choose as a senior citizen). The list from the department of motor vehicles will miss seniors who do not drive, tax rolls will miss those who do not file taxes, etc...
Assuming we can get a complete list (census data perhaps) then we assign each person a unique number. Then we use random number list. Choosing a starting place in the list at random, we then read off the numbers in order. (If there are 2 million seniors, then we take 6 numbers at a time from the list.)
Discard any unused numbers or repeats.
Having determined the number of seniors we need to contact, we get at least that many identifiers, then attempt to contact them for the survey.
(b)Systematic sample: Using the list created in (a), contact every 100th person on the list.
(c) Convenience sample: Go into a few senior citizen homes and interview/survey the residents.