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L.Interviewers were contacting the people who had been selected in a stratified sample. Many of the people they contacted refused to answer their questions. What type of bias Is this? A Non-response blas B. Undercoverage blas C. Interviewer bias Cp] Question wording bias 2. Two variables are confounded when "A, they Interact in their effects on the response variable. B. the effect of one variable impacts the other variable. " C. the effect of one variable on the response variable cannot be separated from the effect of the other variable on the response variable. D. both variables are classified as lurking variables 3. A control group where a placebo is administered to each individual allows the researcher to determine A. The amount of bias in the experimental results. B. Whether the treatment really worked or whether the subjects responded to a placebo effect. C. How to match the individuals in the treatment group with the individuals in the control group. " D. The effects of the lurking variable on the response variable, 4. Blocking should be used whenever "A. you want to remove variation associated with the blocking variable from the experimental variation. B. individuals are grouped before the experiment begins according to some characteristic that is expected to affect the response variable. C. individuals are similar within the blocks but very different from block to block. D.all of the above. 5. Why do we use replication in experiments? A. To eliminate bias associated with lurking variables. B. To enhance the placebo effect. C. To enable the measurement of treatment differences, D. To remove extraneous variation from the experiment error. E To more precisely measure chance variation. 6.Probability samples are samples selected in such a way that A. JEach member of the population has an equal chance of being selected. B. All samples of size n have the same chance of being selected. C. Each member of the population has a chance of being selected and that chance can be computed. D. The sample is guaranteed to duplicate the entire population