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Do Now 12/5/12 Take out HW from last night. – Punchline worksheets 107 Copy HW in your planner. – Text p. 288, #1-3, 5-7, 9-11 all Complete the Exploration activity on “Populations and Samples” Homework Punchline worksheet 107 “Why Didn’t the Physics Teacher Marry the Biology Teacher?” THERE WAS NO CHEMISTRY 2) 1) O. E. T. H. 25 36 44 52 A. I. E. C. R. 83 77 92 35 50% 3) 4) T. 64 E. 61 S. 65 Y. 62 R. 59 H. 63 N. 5 S. 71 W. 341 M. 13 Objective SWBAT compare and analyze sampling methods. Section 7.3, “Populations and Samples” When information is gathered about a group, the entire group is called a Population. Sample part of a population that is representative of the whole population. Types of Samples For a random sample, members of the population are chosen at random. This gives every member of the population an equal chance of being chosen. A convenience sample is based on members of the population that are readily available. Determine which sampling method will better represent the entire population. Justify your answer. Sampling method Maria surveys only the band students she knows personally. Jon writes each band student’s name on a card. He questions those students whose name he draws. Results 84% want blue uniforms 61% want blue uniforms Jon’s sample is a random sample, giving every band member equal chance to be surveyed, so it is the better method. Maria’s sample is a convenience sample and therefore, could be biased. Determine which sampling method will better represent the entire population. Justify your answer. Sampling method Ferdinand surveys every other swimmer on the team. Anna-Maria questions the swimmers who are in her Biology class. Results 72% want practice early 50% want practice early Ferdinand’s sample is a random sample, giving results that better represent the entire swimming team, so it is the better method. A biased sample is a sample taken that does not fairly represent the whole population. A survey is given to 7th grade students who live in Ocean county NJ regarding how many times a 7th grade student living in the United States visits the beach in the summer time. Mickey Mouse takes a survey outside of the Magic Kingdom regarding favorite places to vacation. Determine whether each sample may be biased. Explain. The mayor surveys 100 supporters at a rally about the most important issues to be addressed by the city council. The sample is biased. The supporters may have different ideas than those not at the rally. Determine whether each sample may be biased. Explain. The principal sends out questionnaires to all of the students to find out what kind of music students prefer at dances. The sample is random. The students all have a chance to respond. Determine whether each sample may be biased. Explain. The owner of a record shop surveys only customers over the age of 18 who shop at his store. The survey is biased and is not random. Customers under the age of 18 do not have a chance of being chosen. Verifying Claims Based on Statistical Data A principal of a school with 1,500 students estimates that about 400 students will attend a band festival on Saturday. A random sample of 25 students showed that 6 of them will attend. Determine whether the principal’s estimate is likely to be accurate. Set up a proportion to predict the total number of students that will attend. Students attending sample = Students attending # of Students sampled Student Population 6 = x The estimate is not accurate 25 1500 because the data shows that 360 360 = x students are likely to attend. Verifying Claims Based on Statistical Data The owner of a large chain restaurant with 1,200 employees estimates that about 250 employees will ask for winter vacation. A random sample of 40 employees showed that 8 of them will ask for the time off. Determine whether the owner’s estimate is likely to be accurate. Set up a proportion to predict the total number of employees asking for time off. Employees surveyed for time off = Employees asking for time off # of Employees surveyed Total # of Employees 8 = x 40 1200 240 = x The estimate is accurate because the data shows that 240 employees will ask for time off. NJASK7 Prep Homework Text p. 288, #1-12 all, 17 Homework Punchline worksheets 103 & 107 “What Do You Get When You Cross the Atlantic with the Titanic?” HALFWAY “Why Didn’t the Physics Teacher Marry the Biology Teacher?” THERE WAS NO CHEMISTRY