2Chapter 4 DataData - facts and statistics collected together for reference or analysisSurveys - a way of getting data and recording it.
3Identify three thingsA fitness magazine printed a readers’ survey. Statements 1, 2, and 3 are interpretations. Which do you think the magazine would use?The population is the entire group being studied.The sample is the part of the population being surveyed.A biased sample is when there is not a good representation of the population.
4An eighth-grade student council member polls classmates about a new WG school mascot. She wants to change the mascot from the wolverines to the wolves.
5Population Sample Possible Bias Identify the population and the sample. Give a reason why the sample could be biased.An eighth-grade student council member polls classmates about a new WG school mascot. She wants to change the mascot from the wolverines to the wolves.PopulationSamplePossible BiasStudents in the schoolClassmatesShe polls more eighth-graders than students in other grades.
6Population Sample Possible Bias Identify the population and the sample. Give a reason why the sample could be biased.A music store manager asks customers who make a purchase how many hours of music they listen to each day.PopulationSamplePossible BiasCustomers who make a purchase might be more interested in music than others in the storeMusic store customersCustomers who make a purchase
7Population Sample Possible Bias Try This: 1Identify the population and the sample. Give a reason why the sample could be biased.The first 5 people leaving a movie theater were asked how they liked the movie.PopulationSamplePossible BiasPeople that really enjoy a movie are less likely to be one of the first ones to leave.People that went to the movieThe first five people that left
8Population Sample Possible Bias Try This: 2Identify the population and the sample. Give a reason why the sample could be biased.Eighth-grade students with a 3.0 GPA or higher were polled to determine how long students in the eight grade study each day.PopulationSamplePossible BiasEighth grade studentsStudents with 3.0 or higher GPAStudents with lower grades are less likely to study as long.
9Population Sample Possible Bias Try This: 3Identify the population and the sample. Give a reason why the sample could be biased.People attending a baseball game were asked if they support the construction of a new stadium in the city.PopulationSamplePossible BiasPeople that attend a baseball game are more likely to support the construction of a new stadium.City residentsPeople attending a game
10Population Sample Possible Bias Identify the population and the sample. Give a reason why the sample could be biased.A television reporter asks people on downtown streets if they support a new city subway system.PopulationSamplePossible BiasPeople in the cityPeople on downtown streetsPeople working downtown might show more support than people who work elsewhere.
11According to a rule or formula Systematic Sampling MethodHow Members Are ChosenRandomBy chanceAccording to a rule or formulaSystematicAt random from randomly chosen subgroups. (Double Random)Stratified
12Identifying Sampling Methods Identify the sampling method used.In a Geauga county survey, Democratic Party members whose names begin with the letter D are chosen.systematicThe rule is to survey members whose names begin with D.
13Identifying Sampling Methods Identify the sampling method used.A cable company randomly chooses customers to survey about its service.randomCustomers are chosen by chance.
14Identifying Sampling Methods Identify the sampling method used.A high school randomly chooses three classes from each grade and then draws three random names from each class to poll about lunch menus.stratifiedThe three classes are the random subgroups. Names are chosen randomly from within the classes.
15Identify the sampling method used. Try This: 1Identify the sampling method used.In a county survey, families with 3 or more children are chosen.systematicThe rule is to survey families with 3 or more children.
16Identifying Sampling Methods Identify the sampling method used.A teacher pulls three names out of a hat to decide what students do not have homework.randomStudents are chosen by chance.
17Identify the sampling method used. Try This: 3Identify the sampling method used.At a basketball game 5 sections are chosen at random and 20 people from each section are randomly polled.stratifiedThe five sections are the random subgroups. 20 people are chosen randomly from within the sections.
18Population Sample Possible Bias Lesson Quiz: Part 1Identify the population and sample. Give areason why the sample could be biased.1. A high school principal asks the first three people who leave the school play whether they liked it.PopulationSamplePossible BiasPeople who attended the playThe first 3 people leavingPeople that enjoy a play may not leave as early as someone who didn’t.
19Lesson Quiz: Part 2Identify the sampling method used.2. At a baseball game, 10 sections are chosen at random and 10 random people from each section are polled.3. A telemarketer calls the people that have a last name beginning with H.stratifiedsystematic
20MeanAverageThe sum of the values, divided by the number of valuesMedianHalfway point, MiddleOdd- the middle valueEven- the average of the two middleModeMost Often (value or values)(Put in order)RangeDifference between largest and smallest valueLargest Value minus the smallest value20, 48, 34, 48, 25, 35, 49, 20, 24Mean-Mode-Median-Range-33.6720,483429
21Identify the sampling method used. Try This: 2Identify the sampling method used.A retail home improvement store randomly selects customers to take a survey about their shopping experience.randomCustomers are chosen by chance.