In this design, units need not have equal chances of being selected and some strata may be deliberately oversampled. For example, in the first National Health and Nutrition Examination Survey (NHANES I), the elderly, persons in poverty areas, and women of childbearing age were oversampled to ...
To find this out, you need to be clear about who does and doesn’t fit into your group. For example, if you want to know about dog owners, you’ll include everyone who has at some point owned at least one dog. (You may include or exclude those who owned a dog in the past, dep...
This article addresses test and experimental design issues in the context of testing offers. Using a simple example, we discuss sample size issues first. In this context, we introduce the problem of multiple comparisons and discuss the Bonferroni, Tukey, and Bechhofer approaches. This leads us to...
wheres(t, n — 1) is the probability density for the Student distribution withn — 1degrees of freedom. By determining the correspondingtωfor givennand ω (0 < ω < 1), which may be done, for example, by using tables, we obtain rule (1) for finding the confidence limits forawith...
Your desired sample size depends on what you are measuring and the size of the error that you’re prepared to accept. For example: To estimate a proportion in a population: Sample size =[ (z-score)² × p(1-p) ] ÷ (margin of error)² ...
As an example, we can test a new product on a sample size that is typical of the target population in order to forecast how the people in a certain age group will respond to it. The number of participants in that age group who will be polled in this situation will determine the sample...
"For example, GoMars can simulate the temperatures of the landing zone, and scientists can use these data to design materials that are suitable for building Mars rovers to cope with extreme cold," Wang explained.■
It's often a screening question to filter those who don't fit the needs of the research. Dichotomous question example: For example, you want to know information about people who use your products. This type of question screens respondents to determine if they own your products. Those who ...
A well-formulated research question contains essential information for the sample size calculation. For example, in the Veterans Affairs Keratinocyte Carcinoma Chemoprevention (i.e., VAKCC) Trial, the investigators ran a randomized controlled trial to respond to the question Does the use of 5-fluorou...
A typical example is to divide a set of available samples into design and test sets. In this case, we must assure that design and test distributions are similar. Nonparametric Data Reduction Generally, it is not appropriate to assume a mathematical structure when the sample size is reduced. ...