176 book and lecture 10 What is an over sample What is a mirror sample and how

176 book and lecture 10 what is an over sample what

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(p.176) (book and lecture)10. What is an over-sample? What is a “mirror sample” and how does it permit us to over-sample from ageneral population? When we statistically “weight” data, what do we do? Why do we weight data? (lecture)11. What is nonprobability “sampling”? (p.112) Be able to define, provide an example, and describe the difficulties with each of the four different types of nonprobability “samples”. (p.121-124) Under what circumstance do we use purposive “sampling”? How does it differ from deviant “sampling” and sequential “sampling”? Why are social scientists interested in snowball “sampling”? (book and lecture)12. Describe the process you would use to draw a random sample of residents of Orem, Utah. (Review the four probability sampling methods.) What special problems would you face if you wanted to draw a sample of Utah? The United States? How would you solve them? (student thought)13. What are the advantages and disadvantages of internet panels? (lecture)14. Be able to define key terms for this chapter. (see Key Terms)2. Sampling- a small portion can reveal quality of a larger whole, valid generalizations about a whole.Population- the entire group you wish to learn aboutSample- a subset of the population that we want to learn aboutElements- ind. Members of sampleSampling frame- list of all elements or other units containing the elements in a pop
Sampling unit- units listed at each stage of a multistage sampling design. Target population- set of elements larger than or different from the pop sampled and to which the researcher would like to generalize study findings Representative sample- sample that looks like the population from which it was respected . the distribution of characteristics is same as those among total population. In an unrepresentative sample, some characteristics are overrepresented or underrepresented Parameter- describes a population Statistic- describes a sample 4.probability sampling method (random sampling method)- relies on a random or chance selection method so that the probability or selection of population elements is known 2 problems 1.if sampling frame is incomplete, a sample selected randomly from that list will not really be a random sample of the pop. 2. nonresponse is a major hazard because nonrespondents are likely to differ systematically from those who take the time to participate. Random number table- list of numbers that are ordered soley on the basis of chance, it is used for drawing a random sample 6.the larger the sample size, the more confidence we can have in the samples representativeness, the more homogenous the population, the more confidence we can have in the representatives of a sample of any particular size 7. The proportion of the the pop. that the sample represents does NOT affect sample representativeness 8.4 types of probability methods (random) 1.simple random sampling-ever y sample element is selected only on the basis of chance through a random process. Ex- flipping coin or rolling dice (not the most efficient way) better way- random