1 00:00:00,000 --> 00:00:02,455 MALE NEWS PRESENTER 1: A major winter storm [OVERLAPPING] 2 00:00:02,455 --> 00:00:05,340 MALE NEWS PRESENTER 2: The bruising fight [NOISE] to win Tuesday's Republican [OVERLAPPING] 3 00:00:05,340 --> 00:00:07,960 MALE NEWS PRESENTER 3: Most dangerous virus. [NOISE] 4 00:00:09,050 --> 00:00:13,050 MR GINGRICH: With your help, we're going to win a historic victory. 5 00:00:13,050 --> 00:00:17,060 FEMALE NEWS PRESENTER: The 2012 presidential campaign is in full swing, 6 00:00:17,060 --> 00:00:20,370 with Republican candidates battling state by state to 7 00:00:20,370 --> 00:00:23,850 determine who will face President Barack Obama on election day. 8 00:00:23,850 --> 00:00:26,910 MALE NEWS PRESENTER 4: In the poll numbers we are debuting tonight, 9 00:00:26,910 --> 00:00:29,770 there is a new GOP front-runner in this race. 10 00:00:29,770 --> 00:00:33,930 FEMALE NEWS PRESENTER: A crucial part of this grueling electoral process is polls, 11 00:00:33,930 --> 00:00:36,930 the almost daily snapshots of public opinion, 12 00:00:36,930 --> 00:00:40,290 that help measure who's up and who's down among the candidates. [MUSIC] 13 00:00:40,290 --> 00:00:42,470 PRESIDENTIAL CANDIDATE: Thank you. 14 00:00:42,470 --> 00:00:47,440 DR VINCENT HUTCHINGS: The aim of an opinion poll is to get a sense about a population and where they [NOISE] 15 00:00:47,440 --> 00:00:52,670 stand on some particular set of issues or policies to measure their attitudes and effect. 16 00:00:52,670 --> 00:00:53,920 FEMALE NEWS PRESENTER: [MUSIC] Vincent Hutchings, 17 00:00:53,920 --> 00:00:57,940 an NSF-funded professor of political science at the University of Michigan, 18 00:00:57,940 --> 00:01:03,420 says that public opinion polls rely on a concept in statistics known as random sampling. 19 00:01:03,420 --> 00:01:06,800 The idea that it is possible to draw a clear picture about 20 00:01:06,800 --> 00:01:10,860 the feelings of a large group of people by examining how a small, 21 00:01:10,860 --> 00:01:14,190 randomly assembled slice of that group feels. 22 00:01:14,190 --> 00:01:19,470 DR VINCENT HUTCHINGS: The process involves interviewing a very small subset of that population 23 00:01:19,470 --> 00:01:25,035 and doing so in a scientific manner so that you'll have a better accurate sense 24 00:01:25,035 --> 00:01:26,670 but more efficient sense, 25 00:01:26,670 --> 00:01:29,170 of what the entire population understands. 26 00:01:29,170 --> 00:01:32,220 FEMALE NEWS PRESENTER: An opinion poll might focus on a particular state, 27 00:01:32,220 --> 00:01:37,735 such as Florida, or the entire US population of more than 300 million people. 28 00:01:37,735 --> 00:01:41,500 Pollsters use computer programs to generate a random list of 29 00:01:41,500 --> 00:01:45,500 a few hundred or a few thousand telephone numbers from the larger group. 30 00:01:45,500 --> 00:01:50,040 Then they call each number to survey people for their opinions. 31 00:01:50,040 --> 00:01:53,920 Hutchings says making a random sample is a lot like cooking soup. 32 00:01:53,920 --> 00:01:56,960 You don't need to eat the whole pot to know if it tastes good, 33 00:01:56,960 --> 00:01:59,345 you just need a spoonful. 34 00:01:59,345 --> 00:02:03,580 DR VINCENT HUTCHINGS: The cook merely needs to get a spoon out, taste it. 35 00:02:03,580 --> 00:02:05,860 That spoon represents a sample, 36 00:02:05,860 --> 00:02:08,920 as it were, of the actual contents of the pot. 37 00:02:08,920 --> 00:02:12,450 FEMALE NEWS PRESENTER: [MUSIC] Samples, in general, give better poll results when they include 38 00:02:12,450 --> 00:02:14,770 more characteristics of the whole population 39 00:02:14,770 --> 00:02:17,950 and in the same proportions as the population. 40 00:02:17,950 --> 00:02:19,790 Back to the soup analogy, 41 00:02:19,790 --> 00:02:21,430 if you're cooking chicken soup, 42 00:02:21,430 --> 00:02:24,530 you want your sample to include the ingredients such as chicken, 43 00:02:24,530 --> 00:02:28,865 noodles, and broth in the same proportions as the overall soup. 44 00:02:28,865 --> 00:02:32,230 DR VINCENT HUTCHINGS: We want to make sure that the sample has 45 00:02:32,230 --> 00:02:35,390 the population characteristics that are 46 00:02:35,390 --> 00:02:39,815 demonstrated in the larger population to which we want to make an inference. 47 00:02:39,815 --> 00:02:43,860 FEMALE NEWS PRESENTER: When reading a poll, it's important to also study the fine print, 48 00:02:43,860 --> 00:02:45,460 usually at the bottom. 49 00:02:45,460 --> 00:02:48,120 You'll find information there about how the poll was 50 00:02:48,120 --> 00:02:51,375 conducted and what the size of the random sample was. 51 00:02:51,375 --> 00:02:54,000 You'll also find the margin of error, 52 00:02:54,000 --> 00:02:56,880 a number with a plus or minus sign in front of it. 53 00:02:56,880 --> 00:03:00,025 This number tells you the range of accuracy of the poll. 54 00:03:00,025 --> 00:03:02,940 In this case, 3-5% points. 55 00:03:02,940 --> 00:03:05,580 Typically, the smaller the margin of error, 56 00:03:05,580 --> 00:03:07,730 the more accurate the poll is. 57 00:03:07,730 --> 00:03:12,020 DR VINCENT HUTCHINGS: What that means is that the number that's reported in that survey, 58 00:03:12,020 --> 00:03:15,780 we have a sense that given the size of the sample, 59 00:03:15,780 --> 00:03:19,450 and given the level of uncertainty associated with that size, 60 00:03:19,450 --> 00:03:23,755 the number could be 3-5% points higher or lower. 61 00:03:23,755 --> 00:03:25,770 But we know it's in that range. 62 00:03:25,770 --> 00:03:27,440 FEMALE NEWS PRESENTER: [MUSIC] Even though the polls rely on 63 00:03:27,440 --> 00:03:30,840 just a slice of the population to gauge public opinion, 64 00:03:30,840 --> 00:03:34,200 they are far more accurate than you might think. 65 00:03:34,920 --> 00:03:39,875 [NOISE] Which is one reason why they play such a special role in politics. 66 00:03:39,875 --> 00:03:43,900 DR VINCENT HUTCHINGS: Public opinion polls provide us with a way 67 00:03:43,900 --> 00:03:49,855 absent an actual election to discern where the public stands on various issues. 68 00:03:49,855 --> 00:03:52,620 FEMALE NEWS PRESENTER: As election day 2012 draws closer, 69 00:03:52,620 --> 00:03:55,100 the science of public opinion polls will help give 70 00:03:55,100 --> 00:03:59,920 a clear snapshot of who might be our next president.