Lying about age Pew Research, in November 2011, polled a random sample of 799 U.S. teens about Internet use. 49% of those teens reported that they had misrepresented their age online to gain access to websites and online services. a) Find the margin of error for this poll if we want 95% confidence in our estimate of the percent of American teens who have misrepresented their age online. b) Explain what that margin of error means. c) If we only need to be 90% confident, will the margin of error be larger or smaller? Explain. d) Find that margin of error. e) In general, if all other aspects of the situation remain the same, would smaller samples produce smaller or larger margins of error?

STAT 110 – Notes for Week of 9/6/16 Chapter 6 Continued o You can only generalize results (apply statistics from a sample to an entire population) if the results are: Statistically significant Useful The sample that produced the results is representative of the population The experiment that produced the results was similar enough to real life o Completely Randomized Experimental Design: a type of experimental design where all of the subjects are randomly allocated among the treatments. This type of design allows more than one treatment (treatment combinations) to be isolated and studied at the same time.