### Exercise 4: Biased sampling Bias threatens to undermine the aims of observational studies, but what factors lead to bias vary between different kinds of observational research. Some sampling strategies are unreliable in every case, while others may fail to produce representative samples depending on the context. For each of the sampling strategies below, provide a short response (2-3 sentences) identifying what leads to biased sampling. This may include direct citations from your textbook, but if you do, properly cite it by putting quotation marks around the quote and including "Die; et a1, 2009: [page numberCs)]\" in parentheses. a) Convenience samples should never be trusted to produce a representative sample. Why not? *Write your answer here after deleting this sentence* b) Simple random sampling can produce representative samples, but if response rates are low, bias may creep in. Why? *Write your answer here after deleting this sentence* c) Both stratified sampling and cluster sampling may be applied when a population can be divided into distinct suppgpulgtions. However, stratified sampling is more appropriate in some situations than cluster sampling. If cluster sampling were applied in a situation where stratified sampling would have been more appropriate, biased estimates of population parameters wmgy result. Why? *Write your answer here after deleting this sentence*