A poll checking on the level of public support for proposed antiterrorist legislation reported that 68% of the respondents were in favor. The pollsters reported a sampling error of ±3%. When the responses were broken down by party affiliation, support was 2% higher among Republican respondents than Democrats. The pollsters said the margin of error for this difference was ±4%.
a) Why is the margin of error larger for the difference in support between the parties than for the overall level of support?
b) Based on these results, can we conclude that support is significantly higher among Republicans? Explain.