Homework ReviewIntroductionSimple Random SamplesSelecting SamplesOn the TI-83Setting the SeedAssignmentSimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentSimple Random SamplingLecture 7Section 2.5Robb T. KoetherHampden-Sydney CollegeMon, Jan 26, 2009SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentOutline1Homework Review2Introduction3Simple Random Samples4Selecting SamplesOn the TI-83Setting the Seed5AssignmentSimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentHomework ReviewExercise 9, p. 98In a recent poll, 62% responded “Yes” when asked ifthey favored an amendment protecting the life of anunborn child.However, when asked whether they favored anamendment prohibiting abortions, 39% said “Yes.”What type of bias is being observed?SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentHomework ReviewSolutionThe respondents are giving their answer based on theirperception of the question.When the question refers to “protecting life,” they are infavor of that, so they are more likely to say “Yes.”When the question refers to “prohibiting abortion,” theyare opposed that, so they are less likely to say “Yes.”SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentIntroductionRecall that randomness in a large sample ensuresrepresentativeness, within a very small sampling error.That is because the vast majority of possible samplesare representative.If we pick a sample at random, we are bound to get onethat is representative.SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentIntroductionRecall that randomness in a large sample ensuresrepresentativeness, within a very small sampling error.That is because the vast majority of possible samplesare representative.If we pick a sample at random, we are bound to get onethat is representative.SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentIntroductionRecall that randomness in a large sample ensuresrepresentativeness, within a very small sampling error.That is because the vast majority of possible samplesare representative.If we pick a sample at random, we are bound to get onethat is representative.SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentIntroductionHow could I use a coin to select a random sample of 3students from this class?By this method, do all individuals have equal chances?Do all samples have equal chances?How could I accomplish the same using a die?SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentIntroductionHow could I use a coin to select a random sample of 3students from this class?By this method, do all individuals have equal chances?Do all samples have equal chances?How could I accomplish the same using a die?SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentIntroductionHow could I use a coin to select a random sample of 3students from this class?By this method, do all individuals have equal chances?Do all samples have equal chances?How could I accomplish the same using a die?SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentIntroductionHow could I use a coin to select a random sample of 3students from this class?By this method, do all individuals have equal chances?Do all samples have equal chances?How could I accomplish the same using a die?SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentSimple Random SampleDefinition (Simple random sample)A simple random sample of size n is a random sample thatis selected in such a way that all samples of size n have thesame chance of being selected.SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentSimple Random SampleA consequence of this is that all individuals in thepopulation have the same chance of being selected forthe sample.SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentSimple Random SampleExample (Simple Random Sample){A, B, C} {A, C, D} {A, D, F} {B, C, F} {C, D, E}{A, B, D} {A, C, E} {A, E, F} {B, D, E} {C, D, F}{A, B, E} {A, C, F} {B, C, D} {B, D, F} {C, E, F}{A, B, F} {A, D, E} {B, C, E} {B, E, F} {D, E, F}For example, let the population be {Anthony, Benjamin,Christopher, Destiny, Emily, Faith}.Choose one of the above samples at random.What is each person’s chance of being in the sample?SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentSimple Random SampleHowever, that does not work the other way around.Just because a sampling method guarantees that allindividuals in the population have the same chance ofbeing in the sample, it does not mean that the sampleis a simple random sample.SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentSimple Random SampleExample (Simple Random Sample)Toss a coin to choose one of the following samples.What is each person’s chance of being in the sample?{A, B, C} {D, E, F}SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentSimple Random SampleOur method will be to select individuals one at a time,with all individuals equally likely at each step.By this method, all samples are equally likely.Thus, our sample will be a simple random sample.SimpleRandomSamplingRobb T.KoetherHomeworkReviewIntroductionSimpleRandomSamplesSelectingSamplesOn the TI-83Setting the SeedAssignmentSelecting a Simple Random SampleGiven a population of size N ,Number the
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