Chapter+9

Chapter 9

Below are four populations and a potential sample frame for each. For each pair, identify: (1) members of the population who are not in the sample frame, and (2) members of the sample frame items who are not part of the population. Also, for each one, would you judge the amount of sample frame error to be acceptable or unacceptable? Give reasons for your answers. __ Population __ - Entire group under study __ Sample Frame __ – Master list of the population __ Sampling Error __ - Error due to method of sample selection or size of the sample __ Sample __ – Subset of the population
 * CHAPTER 9 - QUESTION 1.3 **
 * ** Population ** ||  ** Sample Frame **  ||
 * * Buyers of Scope mouthwash
 * Listeners of a particular FM radio classical music station
 * Prospective buyers of a new day planner and prospective-client tracking list
 * Users of weatherproof decking materials to build outdoor decks || * Mailing list of //Consumer Reports// subscribers
 * Telephone directory into your city
 * Members of Sales and Marketing Executives International ( a national organization of sales managers)
 * Individual names registered at a recent home and garden show ||

2.Those who do not use Scope mouthwash but are part of the mailing list for //Consumer Reports// are not part of the population
 * A. ** 1.Those who are not on the mailing list or read //consume reports// but do use Scope mouthwash are not in the sampling frame
 * B ** . 1.Those who are unlisted or private but listen to the FM classical radio station are not in the sampling frame

2. Those who do not listen to classical FM music station but are part of the telephone directory in the city are not part of the population

the sampling frame
 * C ** . 1. Those who are not members of Sales and Marketing Executives International are not in

2. Those who are not looking to buy a day planner and are not on a tracking list are not in the population


 * D ** . 1. Those who do not use weather proof decking materials but went to the home and garden show are not in the sampling frame

2. Those who use weather proof decking materials but did not go to the home and garden show

2.4: An online company selling used textbooks to post-secondary students wants to research the growth rate of its market in Canada. The company conducted a survey of used-book buying by students each year for the past four years. In each survey, 1000 randomly selected students were asked to indicate whether they bought a used textbook in the previous year. The results were as follows:

__Years ago__


 * |||||||| Years Ago  ||
 * || 1  ||  2  ||  3  ||  4  ||
 * % buying used text(s) ||  70%  ||  60%  ||  55%  ||  50%  ||

Assess whether or not the survey should be continued in the coming year with a sample size of 1000. Is the sample size of 1000 adequate for the company's analysis? Give reasons for your answer.


 * A sample size of 1000 is adequate for the company's analysis and they do not need a larger sample size because increasing the sample size from 1000 to 2000 (for example) does not significantly improve the accuracy of the results.
 * See chart on pg.295

2.3: Crest toothpaste is reviewing plans for its annula survey of toothpaste purchasers. With each case that follows, calculate the sample size pertaining to the key variable under consideration. Where information is missing, provide reasonable assumptions. A) A telephone survey using drop-down replacement of nonrespondents B) A mail survey with an anticipated 30% response rate (assume the incidence rate for this sample frame to be 100%) A) Skip Interval = 15000/1000 = 15  B) Skip Interval = 15000/(1000x[1/1]x[1/0.30]) = 4.5 or 5 people
 * Case 1:** Market share of Crest toothpaste last year; variability= 23% share, acceptable error= 4%, confidence level= 95%
 * ANSWER:** 421
 * Case 2:** Percentage of people who brush their teeth per week; variability= unknown, acceptable error= 5%, confidence level = 99%
 * ANSWER:** 666
 * Case 3:** How likely Crest buyers are to switch brands; variability= 30% switched last year, acceptable error= 5%, confidence level= 95%
 * ANSWER:** 426
 * Case 4:** Percentage of people who want tartar control; variability= 20% 2 years ago & 40% 1 year ago, acceptable error= 3.5%, c.level= 95%
 * ANSWER:** 777 & 777
 * Case 5: W**illingness of people to adopt the toothpaste; variability= unknown, acceptable error= 6%, confidence level= 99%
 * ANSWER:** 463
 * 3.3 ** Pet Insurers markets insurance to pet owners. It specializes in coverage for pedigreed dogs, cats and exotic pets such as miniature Vietnamese potbellied pigs. The veterinary costs of these pets can be high, and their deaths represent substantial financial loss to their owners. A researcher working for Pet Insurers finds that a listing company can provide a list of 15000 names that includes all current subscribers to //Cat Lovers, Pedigreed Dogs// and //Exotic Pets Monthly.// If the final sample size is to be 1000, calculate what the skip interval should be in a systematic sample for each of the following:
 * Answers: **
 * Systematic sampling ** is a way to select a simple random sample from a directory or list that is much more efficient than with simple random sampling. The goal of systematic sampling is to literally “skip” though the list in a systematic way, but to begin at a random starting point in the list. That is, the research calculates a “**skip interval**” using the following formula:
 * Skip interval = Population list size/Sample Size **
 * Skip interval = Population list size/Adjusted sample size **
 * Where: Adjusted sample size = Sample size x (1/Incidence rate) x (1/Response rate) **

====**4.3:** A market researcher is proposing a survey for a private country club that is contemplating several changes in its layout to make the golf course more championship caliber. The researcher is considering three different sample designs as a way to draw a representative sample of the clubs golfers. The three alternative designs are:==== Assess the representativeness and other issues associated with this sample problem. Be sure to identify the sample method being contemplated in each case. Which sample method do you recommend using, and why?
 * A.** Station an interviewer at the first-hole tee on one day chosen at random, with instructions to ask every tenth golfer to fill out a self-administered questionnaire.
 * B.** Put a stack of questionnaires on the counter where golfers check in, and pay for their golf carts. There would be a sign above the questionnaires, and there would be an incentive for a "free dinner in the clubhouse" for three players who fill out the questionnaire and whose names are selected by a lottery.
 * C.** using the city telephone directory, a plus-one dialling procedure would be used. With this procedure a random page in the directory would be selected, and a name on that page would be selected, both using a table of random numbers. The plus-one system would be applied to that name and every name listed after it until 1000 golfers are identified and interviewed by telephone.
 * Answer:**
 * A.** Is a Nonprobability sampling method: Quota Sample - The major problem with this method is that you are asking golfers who are ready to go and play a game of golf to stop and fill out a questionnaire, its taking away their golf time and has no perceived value to the golfer.
 * B.** Nonprobability Sampling method: Convenience sampling - This would be in my opinion the most effective way of doing this research because it gives the golfers the option to do the survey, its not taking away from their game time, and it offers a reward for feeling out ther survey, which may get more of the golfers to fell it out.
 * C.** Probability Sampling Method: Simple Random Sampling - This would seem to take to long, it seems ineffective especially because they already have access to their target sample which is the golfers, and they can have access to them at the golf course. It would take to long and its not guaranteed that even if you find golfers by calling them that they will want to do the survey.