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Chapter 1: Q 1.29. (page 15)
In sampling, explain why obtaining a representative sample is important.
A representative sample is important to reflect as closely as possible the relevant attributes of the entire population under study.
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The members of a population have been numbered 1-500. A sample of size 10 is to be taken from the population, using stratified random sampling with proportional allocation. The strata are of sizes 200, 150, and 150, where stratum #1 consists of the members of the population numbered 1-200, stratum #2 consists of the members of the population numbered 201-350, and so forth.
(a) Determine the sample sizes that will be taken from the strata.
(b) Apply Procedure 1.3 on page 21 to determine the sample (i.e., the numbers corresponding to the members of the population that are included in the sample).
Lifetimes of Flashlight Batteries.Two different options are under consideration for comparing the lifetimes of four brands of flashlight battery, using 20 flashlights.
(a) One option is to randomly divide 20 flashlights into four groups of 5 flashlights each and then randomly assign each group to use a different brand of battery. Would this statistical design be a completely randomized design or a randomized block design? Explain your answer.
(b) Another option is to use 20 flashlights - five different brands of 4 flashlights-each and randomly assign the 4 flashlights of each sign be a completely randomized design or a randomized block design? Explain your answer.
Nonresponse. When responses are not obtained from some of the individuals in the sample because either those individuals cannot be reached or refuse to participate, we have nonresponse bias.
(a) Discuss some of the dangers of nonresponse.
(b) Many sample surveys that are reported in the media have rates as low as 10%. Explain the consequences of such low response rates in trying to generalize the results to the entire population.
Identify two statistical methods other than a census for obtaining information.
Regarding simple random sampling:
(a) What is simple random sampling?
(b) What is a simple random sample?
(c) Identify two forms of simple random sampling and explain the difference between the two.
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