6.145 Find published studies with confidence intervals. Search the Internet or some journals that report research in your field and find two reports that provide an estimate with a margin of error or a confidence interval. For each report,

1. (a) describe the method used to collect the data.

2. (b) describe the variable being studied.

3. (c) give the estimate and the confidence interval.

4. (d) describe any practical difficulties that may have led to errors in addition to the sampling errors quantified by the margin of error.