EMR 6500: Survey Research. Dr. Chris L. S. Coryn Kristin A. Hobson Spring 2013. Agenda. Simple random sampling Crafting good questions Midterm examination Case Study #1 Case Study #2. Simple Random Sampling. Simple Random Sample.
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Dr. Chris L. S. Coryn
Kristin A. Hobson
Simple random sampling
Crafting good questions
Case Study #1
Case Study #2
Recall that a simple random sample is a sample of n elements from a population of N in which each possible sample of size n has the same probability of selection, namely
The probability of any element being selected is equal to the ratio of the sample size to the population size
If n = 200 was selected from N = 1,000 and the sample mean was = 94.22 with a sample variance of = 445.21, the bound on the error of estimation, B, would be
If n = 50 was selected from N = 750 and the sample mean was = 10.31 ( = 750(10.31) = 7,732.5) with a sample variance of = 2.25, the bound on the error of estimation, B, would be
Often, the population variance, , is unknown
An approximate value of can be obtained by
If N = 1,000 and the estimated range is 100, the sample size necessary to estimate with B = 3 would be
If N = 1,000 and = 36.00, the sample size necessary to estimate the population total, , with B = 1,000 would be
If n = 100 was selected from N = 300 and the sample proportion was = 0.15 the bound on the error of estimation, B, would be
If N = 2,000 and the desired bound on the error of estimation, B, were 0.05, and no prior information is available to estimate , the necessary sample size would be
What survey mode(s) will be used to ask the questions?
Is the question being repeated from another survey, and/or will answers be compared to previously collected data?
Will respondents be willing and motivated to answer accurately?
What type of information is the question asking for?
Use darker and/or larger print for the question and lighter and/or smaller print for answer choices and answer spaces
Use spacing to create subgrouping within a question
Visually standardize all answer spaces or response options
Use visual design properties to emphasize elements that are important to the respondent and to deemphasize those that are not
Make sure words and visual elements that make up the question send consistent messages
Integrate special instructions into the question where they will be used rather than including them as freestanding entities
Separate optional or occasionally needed instructions from the question stem by font or symbol variation
Organize each question in a way that minimizes the need to reread portions in order to comprehend the response task
Choose line spacing, font, and text size to ensure the legibility of the text
Individuals who endorse the first response should also endorse all others as they represent less extreme views