SOCIOL 350 – 02 Exam 2 – Flashcards
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Social scientists gather data from samples instead of populations because
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populations are often too large to test.
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Statistics are to parameters as
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samples are to populations
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There are about 70 million eligible voters in a society. A public opinion pollster has estimated their probable choices for the next president with a sample of 2,000 randomly selected citizens. In this example, the 2,000 citizens are a __________ and the 70 million eligible voters are a _______.
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sample, population
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A researcher tests a theory about sexism by administering a survey to the 200 students in her sociology classes. This sample is best characterized as a
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non-probability example
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The main problem with non-probability samples is that they
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do not allow us to generalize to a population.
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A sample selected according to the principle of EPSEM is extremely likely to be
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representative
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To select a simple random sample, a researcher needs
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a list of the population and system for selecting cases according to EPSEM.
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In systematic random sampling, the researcher randomly selects
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the first case and every kth case thereafter.
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A sampling technique that allows you to ensure proportional representativeness in a sample is
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stratified sampling.
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A major limitation for stratified sampling is that
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the exact composition of the population is usually unknown.
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When a list of the population does not exist, the probability sampling technique most commonly used is
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cluster
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Results from cluster samples
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should be treated with more caution than results from simple random samples.
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The sampling distribution links the ________ to the __________.
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sample, population
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Unlike the sample and population distributions, the sampling distribution is
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theoretical
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The purpose of inferential statistics is to acquire knowledge of the ____________ from the ___________ by means of the _____________ distribution
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population, sample, sampling
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Your sample size is 1000. It is safe to assume that
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the shape of the sampling distribution of sample means is normal.
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When we use larger samples (N > 100) we can assume a normal sampling distribution because of
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the central limit thereom
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In estimation procedures, ___________ are estimated based on the value of ____________.
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parameters, statistic
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The probability that an interval estimate does not include the population value is called
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alpha
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An alpha level of 0.05 is the same as a confidence level of
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95%
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We have used an alpha of 0.01 to estimate the average hours of television viewing for residents in a retirement home. What is the chance that our interval estimate does not contain the true population mean?
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1%
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In constructing interval estimates based on sample proportions (Ps), the population proportion (Pu) must be estimated. It is most conservative to estimate Pu at
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.50
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As our confidence in an interval estimate increases, the width of the interval
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increases
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All tests of hypothesis are based on the assumption that
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the null hypothesis is true
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The research and null hypotheses _________ each other.
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contradict
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In tests of significance, if the test statistic falls in the critical region, we may conclude that
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the null hypothesis can be rejected
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A researcher is interested in the effect that neighborhood crime-watch efforts have on the crime rate in the inner city, but he is unwilling to predict the direction of the difference. The appropriate test of hypothesis would be
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two-tailed
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A one-tailed test of significance could be used whenever
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the researcher can predict a direction
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When testing for the significance of the difference between a sample mean and a population mean, degrees of freedom are equal to
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N-1
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If the test statistic does not fall in the critical region, we
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we fail to reject the null hypothesis
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Inferential statistics (are)
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ways of looking at data that relates to everyone
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Mu is the
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population average
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Statistics used is always referring to
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sample data
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Parameters
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numbers we would like to have, population average, will never have population parameters
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The goal of parameters is to
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estimate what population ... are like
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The best sample is a
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random sample
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A random sample
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best represents the larger population; does not always mean representative
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Epson technique
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steps to ensure sample is representative
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Systematic sample
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random number generator
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Systematic sample works by
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choosing a random number, include all names in a pattern after that (intervals)
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A stratified sample
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guarantees that population is represented proportionally
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What is the problem with a stratified sample?
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We don't know the breakdown of a city (we need to know the exact breakdown) -- getting a list of all residents
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What is a cluster sample?
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selecting a group/region rather than individuals
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What is a multi-stage cluster sample?
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random select school, random select classes, list of students from random classes and schools, random selected students
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What is a problem of a multi-stage sample?
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great chance of misrepresentation/non-representative
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What is a sampling distribution?
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theoretical probable distribution of statistic for all samples of the same size
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What is the central limit theorem?
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as people in sample goes up, the same is more accurate to the larger population level
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What is the standard error?
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standard deviation of our sampling distribution
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What is a two-tailed test?
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setting critical regions at both ends of the curve
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What is a one-tailed test?
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critical region is not distributed, al .05 is on one side, not split
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How do you test the one-tailed test?
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above 1.65 is rejecting null hypothesis
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What is the situation for a one-tailed test?
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depends on a particular direction
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What is the t distribution compared to the z distribution?
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the t distribution is flatter and not as condensed
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What is the appendix for the t distribution?
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appendix B
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What are the degrees of freedom for the t distribution?
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N-1
