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43 Cards in this Set
- Front
- Back
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What is a nonprobability sample?
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A sample that relies of personal judgement
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What are the steps in drawing a sample?
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Define the Problem
Identify the Sampling Frame Select a Sampling procedure Determine sample size Select sampling elements collect data |
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convenience sample
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Accidental Sample
Usually not representative of population |
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Judgment Sample
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purposive
representative of pop or offer contributions sought |
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Quota sample
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proportional to a certain characteristic
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Types of nonprobability sample
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Convenience
Judgment Quota |
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What is a probability sample?
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each population has a known chance to be included
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Types of probability samples
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simple random sample
stratified sample cluster sample |
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simple random sample
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each chosen randomly and each has = chance of being selected
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Probability Sample
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does not involve personal judgment
allows computation of sample size |
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stratified sample
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groups members into subgroups before selecting independently
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cluster sample
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divided into groups then selected randomly
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parameter
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characteristic of a parent or target population
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Statistic
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Characteristic of measure of a sample
Deals with sample mean and variances |
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Precision
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Degree of error in a study
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how does precision relate to determining a sample size
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the more important the decision, the more precise the information needs to be
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How does precision relate to setting a confidence interval?
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There is a trade off between them
can specify one but not both |
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sampling error
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The difference between the observed values of a variable and the long run average of the observed values
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Non sampling error
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Error that arises in research and that is not due to sampling
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Examples of non sampling error
(read) |
poorly written research report
poor problem formulation improper design poor methods inadequate sample design improper use of stats poor logic |
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What is the advantage of taking a sample rather than doing a census?
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Takes less time
Less money |
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How would you estimate sigma (population standard deviation) when it is unknown
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Estimate sigma by:
looking at range (plus/minus 3sigma) Past experience or similar studies Small pretest Conservatively guess |
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What is systematic random sampling? How is it classified?
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sampling every kth (from random number table) of the population.
Classified as cluster sampling |
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What is Probability-Proportional-to-Size (PPS) sampling? Why does each sample member have an equal chance of being selected?
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PPS is selecting first stage units based on population, and using a fixed number for selecting second stage units.
Each sample has an equal chance of being selected because the two probabilities cancel each other out. |
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statistical efficiency
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Measure used to compare sampling plans; the smaller the standard error of estimate the better
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economic efficiency
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cost per observation
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Overall efficiency
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Cluster
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Cluster sampling
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More economically efficient than stratified
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Stratified Sampling
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More statistically efficient than cluster
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What is area sampling?
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Form of cluster sampling
areas serve as primary sampling units population is divided one or two stage area sampling |
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What are the advantage in using (cluster) area sampling?
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Faster
Cheaper More efficient do not need listing of population to draw sample |
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When having multiple objectives how do you determine which sample size to use?
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Most conservative
Most critical variable as large as you can afford |
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For means what do you do when the population variance is unknown?
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Use sample variance
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What are the three variances that are relevant in computing confidence intervals?
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population, sample, sampling distribution
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significance level
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must be under .05, which equals 95% confidence
Answers if the results happened by chance. |
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Cramer's V, PHI, Contingency
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Indicates how strong the relationship is
Under.25 is low .25-.35 is medium over.35 is a strong relationship |
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What are three ways to determine samples size?
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Statistically
Type analysis Budget |
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Calculating %s on contingency tables
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Calculate %s across the dependent variable
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What are ethical issues in marketing research? What are the main categories to classify these issues?
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Researcher/Participant
Researcher/Client |
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Summary
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Most important part of the report
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What is in a research report?
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Title Page
Table of Contents Summary Intro Body Conclusions and recommendations Appendix Synopsis |
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What are some good guidelines when making an oral presentation? How much technical detail should be included?
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try to appeal to the audience
Too little technical stuff is better than too much |
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When and how often should graphics be used?
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Graphics should be used alot
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