Chapter 15 - Sample size and statistical theory. In this chapter, the following content will be discussed: Determining the sample size, factors determining sample size, population characteristics/parameters, sample characteristics/statistics,. | Marketing Research Aaker, Kumar, Leone and Day Twelfth Edition Instructor’s Presentation Slides 1 Chapter Fifteen 2 Sample Size and Statistical Theory Marketing Research 12th Edition Determining the Sample Size Ad Hoc Methods Used when a person knows from experience what sample size to adopt Used when budgetary constraints dictate the size of the sample Rule of Thumb Sample should be large enough, so that when divided into groups, each group will have a minimum sample size of 100 or more If analysis involves comparison between subgroups, sample size in each subgroup should be 20 to 50 Use disproportionate sampling if one of groups of population is relatively small Budget Constraints Researcher must decide whether sample size dictated by budget constraints allows a worthwhile study to be conducted Comparative Studies Find similar studies and use their sample sizes as a guide 3 Marketing Research 12th Edition Factors Determining Sample Size Number of groups and subgroups within the . | Marketing Research Aaker, Kumar, Leone and Day Twelfth Edition Instructor’s Presentation Slides 1 Chapter Fifteen 2 Sample Size and Statistical Theory Marketing Research 12th Edition Determining the Sample Size Ad Hoc Methods Used when a person knows from experience what sample size to adopt Used when budgetary constraints dictate the size of the sample Rule of Thumb Sample should be large enough, so that when divided into groups, each group will have a minimum sample size of 100 or more If analysis involves comparison between subgroups, sample size in each subgroup should be 20 to 50 Use disproportionate sampling if one of groups of population is relatively small Budget Constraints Researcher must decide whether sample size dictated by budget constraints allows a worthwhile study to be conducted Comparative Studies Find similar studies and use their sample sizes as a guide 3 Marketing Research 12th Edition Factors Determining Sample Size Number of groups and subgroups within the sample Value of information in the study Accuracy level required in results Cost of sample Variability of the population 4 Marketing Research 12th Edition Population Characteristics/Parameters Population Mean Normally unknown Determine value as closely as possible by taking a sample from population Population Variance Measure of population dispersion Based on degree to which a response differs from population average response The difference of each value from its mean is squared and averaged across all responses 5 Marketing Research 12th Edition Population Characteristics/Parameters 6 The population opinion on symphony starting time (7:30 . on weekdays) Marketing Research 12th Edition Sample Characteristics/Statistics 7 Sample mean ( ) is used to estimate the unknown population mean Example: A sample of symphony season-ticket holders Marketing Research 12th Edition Sample Characteristics/Statistics (Contd.) 8 Sample mean Marketing Research 12th Edition Sample Reliability X will vary .
