1 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Learning Objectives: 1.Understand the key principles in sampling. 2.Appreciate the difference between the target population and the sampling frame. 3.Recognize the difference between probability and non-probability sampling. 4.Describe the different sampling methods. 5.Determine the appropriate sample size. Sampling Approaches and Considerations Chapter 8

2 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Go On-Line A sample is a relatively small subset of the population that is selected to be representative of the population’s characteristics. A census involves collecting data from all members of a population. Sampling vs. Census ? Sampling vs. Census ?

3 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Sampling Design Process The sampling design process involves answering three questions: 1.Should a sample or a census be used? 2.If a sample, then which sampling approach is best? 3.How large a sample is necessary?

4 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Steps to follow: To obtain a representative sample Define the target population. 2. Choose the sampling frame. 3. Select the sampling method. 4. Determine the sample size. 5. Implement the sampling plan.

5 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Representative Sample A representative sample mirrors the characteristics of the population and minimizes the errors associated with sampling.

6 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, the complete group of objects or elements relevant to the research project. They are relevant because they possess the information the research project is designed to collect. Target Population

7 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, elements or objects available for selection during the sampling process are known as the sampling unit. Sampling Unit

8 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, as complete a list as possible of all the elements in the population from which the sample is drawn. Sampling Frame

9 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, The sampling frame often is flawed because... It may not be up to date. It may include elements that do not belong to the target population. It may not include elements that do belong to the target population. It may be compiled from multiple lists and contain duplicate elements.

10 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Go On-Line Non-Probability Probability Sampling Methods Sampling Methods

11 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Go On-Line Probability vs. Non-Probability Sampling Non-Probability = not every element of the target population has a chance of being selected because the inclusion or exclusion of elements in a sample is left to the discretion of the researcher. Probability = each element of the population has a known, but not necessarily equal, probability of being selected in a sample.

12 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Types of Sampling Methods Probability Simple Random Systematic Stratified Cluster Multi-Stage Non-Probability Convenience Judgment Snowball/Referral Quota

13 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, a sampling method in which each element of the population has an equal probability of being selected. Simple Random Sampling

14 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Systematic Sampling... a process that involves randomly selecting an initial starting point on a list, and thereafter every n th element in the sampling frame.

15 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, requires the researcher to partition the target population into relatively homogeneous subgroups that are distinct and non- overlapping. Stratified Sampling

16 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Two Types of Stratified Sampling Disproportionate = the number of elements chosen from each of the strata is not based on the size of the stratum relative to the target population size, but rather is based either on the importance of a particular stratum or its variability. Proportionate = the number of elements chosen from each of the strata is proportionate to the size of a particular strata relative to the overall sample size.

17 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Cluster Sampling... a form of probability sampling in which the relatively homogeneous individual clusters where sampling occurs are chosen randomly and not all clusters are sampled.

18 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Multi-Stage Cluster Sampling Cluster sampling involves dividing the population into clusters and randomly selecting a pre-specified number of clusters and then either collecting information from all the elements in each cluster or a random sample. With multi- stage cluster sampling the same process is completed two or more times.

19 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Convenience Sampling... involves selecting sample elements that are most readily available to participate in the study and who can provide the required information.

20 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Judgment Sampling... a form of convenience sampling, sometimes referred to as a purposive sample, in which the researcher’s judgment is used to select the sample elements.

21 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, similar to proportionately stratified random sampling but the selection of the elements from the strata is done on a convenience basis. Quota Sampling

22 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, also called a referral sample, the initial respondents typically are chosen using probability methods and these respondents then identify others in the target population. Snowball Sampling

23 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Determining sample size involves achieving a balance between several factors: The variability of elements in the target population. The type of sample required. Time available. Budget. Required estimation precision. Whether findings will be generalized.

24 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Three decisions to make when statistical formulas are used to determine sample size: 1. The degree of confidence (often 95%). 2. The specified level of precision (amount of acceptable error). 3. The amount of variability (population homogeneity).

25 Hair, Babin, Money & Samouel, Essentials of Business Research, Wiley, Sampling Approaches and Considerations Go On-Line How would this website be useful to business researchers?