Should We Believe Statistics??? Lesson #13 Chapter 2

57% of Ameri cans have bough t a lotte ry ticke t in the last 12 month s O Did they actually ask every American about their purchases over the last year?? O How can this statement be made??

O Out of 200 million adults, 1523 people were chosen at random to be surveyed. O Gallup found that 57% of those who took the survey bought lottery tickets in the past 12 months. O Using this fact, they estimated the actions of the 200 million adults. O Your statement will not say how many people were in the survey (it is generalized to the entire population). 1. Determi ne a sample to be surveye d. 2. Give the survey. 3. General ize the results from the sample to the populat ion.

Numbers Parameters Statistics O These are numbers which describe populations. O Their values are usually unknown. O Given as a proportion of the population. O These are numbers which describe samples. O Their values are usually known. O Calculated by the formula for p-hat.

So how accurat e can a survey be anyway? If enough surveys are conduct ed, will the results be similar ?

Let’s Find Out… Should Gambling Be Legal???

Activity 2.2 (pages 83-84) Line 101: 19, 22, 39, 50, 34, 05, 75, 62, 87,13 Which ones were white? 39, 50, 34, 05, 62, 87, 13 Which ones were blue? 19, 22, 75 So p-hat = 0.70 Now do this 9 more times with different lines each time.

Group Work, continued O Make a dot plot of your 10 values for p-hat. O How many of your values were exactly 0.60 (the population proportion)? O Calculate the average of your 10 sample proportions? O Combine your results on the board with the rest of the class (the dot plot and the values). O What is the average of the class p-hat values?