# Shared Flashcard Set

## Details

Statistics
Exam 2 - Chapters 6-10
45
Social Work
11/09/2011

Term
 Central Limit Theorem
Definition
 A theorem that specifies the mean, standard deviation, and shape of the sampling distribution, given that the sample is large. n>100
Term
 Cluster Sample
Definition
 A method of sampling by which geographical units are randomly selected and all cases within each selected unit are tested.
Term
 E.P.S.E.M
Definition
 The Equal Probability of SElection Method for selecting samples.  Every element of case in the population must have an equal probability of selection for the sample.
Term
 μ - mu
Definition
 The mean of a population
Term
 μ -sub- X_ (mu sub mean)
Definition
 The mean of a sampling distribution of sample means.
Term
 μ -sub- p
Definition
 The mean of a sampling distribution of sample proportions.
Term
 P -sub- s
Definition
 Any sample proportion
Term
 P -sub- u
Definition
 Any population proportion
Term
 Representative
Definition
 The quality a sample is said to have if it reproduces the major characteristics of the population from which it was drawn.
Term
 Sampling Distribution
Definition
 The distribution of a statistic for all possible sample outcomes of a vertain size. Under conditions specified in two theorems, the sampling distribution will be normal in shape, with a mean equal to the population value and a standard deviation equal to the population standard deviation divided by the square root of N.
Term
 Simple random sample
Definition
 A method for choosing cases from a population by which every case and every combination of cases has an equal chance of being included.
Term
 Standard error of the mean
Definition
 The standard deviation of a sampling distribution of sample means.
Term
 Stratified Sample
Definition
 A method of sampling by which cases are selected from sublists of the population.
Term
 Systematic Sampling
Definition
 A method of sampling by which the first case from a list of the population is randomly selected.  Thereafter, every kth case is selected.
Term
 Alpha
Definition
 The probability of error, or the probability that a confidence interval does not contain the population value.  Alpha levels are usually set at 0.10, 0.05
Term
 Bias
Definition
 A criterion used to select sample statistics as estimators.  A statistic is unbiased if the mean of its sampling distribution is equal to the population value of interest.
Term
 Confidence Interval
Definition
 An estimate of a population value in which a range of values is specified.
Term
 Confidence Level
Definition
 A frequently used alternate way of expressing alpha, the probability that an interval estimate will not contain the population value.  Confidence Levels of 90%, 95% correspond to alphas of 0.10 and 0.05.
Term
 Efficiency
Definition
 The extent to which the sample outcomes are clustered around the mean of the sampling distribution.
Term
 Point Estimate
Definition
 An estimate of a population value where a single value is specified.
Term
 Alpha Level (2)
Definition
 The proportion of area under the sampling distribution that contains unlikely sample outcomes, given the null hypothesis is true, it is the probability of Type 1 error
Term
 Critical Region (region of rejection)
Definition
 The area under the sampling distribution that, in advance of the test itself, is defined as including unlikely sample outcomes, given that the null hypothesis is true.
Term
 Six Step Model
Definition
 1-make assumptions 2-null and research hypothesis 3-draw picture 4-state alpha, df, and t or z critical 5- compute equation 6-findings
Term
 Hypothesis Testing
Definition
 Statistical tests that estimate the probability of sample outcomes if assumptions about the population (null hypothesis) are true.
Term
 Null Hypothesis (HsubO)
Definition
 A statement of "no difference" in the context of single sample tests of significanece, the population from which the sample was drawn is assumed to have a certain characteristic or value.
Term
 One-Tailed Test
Definition
 A type of hypothesis test used when 1- the direction of the difference can be predicted or 2- concern focuses on outcomes in only one tail of the sampling distribution
Term
 Research Hypothesis (Hsub1)
Definition
 A statement that contradicts the null hypothesis.  In the context of single sample tests of significance, the research hypothesis says the population from which the sample was drawn does not have a certain characteristic or value
Term
 Student's t Distribution
Definition
 A distribution used to find the critical region for tests of sample means when σ is unknown and sample size is small.
Term
 t(critical)
Definition
 The t score that marks the beginning of the critical region of a t distribution
Term
 t(obtained)
Definition
 The test statistic computed in step 5 of the six-step model.  The sample outcome into either a t score or a z score.
Term
 Test statistic
Definition
 The value computed in step 5 of the 6 step model that converts the sample outcome into either a t or z score.
Term
 Two tailed Test
Definition
 a type of hypothesis test used when 1 the direction of the difference cannot be predicted or 2 concerns focus on outcomes in both tails of the sampling distribution.
Term
 Type 1 and Type 2 Errors Alpha and Beta
Definition
 Alpha Error- the probability of rejecting a null hypothesis that is, in fact, false. Beta Error- The probability of failing to reject a null hypothesis that is, in fact, false.
Term
 Independent Random Samples
Definition
 Random samples gathered in such a way that the selection of a particular case for one sample has no effect on the probability that any other particular case will be selected for the other samples.
Term
 Pooled Estimate
Definition
 An estimate of the standard deviation of the sampling distribution of the difference in sample means based on the standard deviation of both samples.
Term
 σp-p
Definition
 symbol for the standard deviation of the sampling distribution of the differences in sample proportions.
Term
 σx-x
Definition
 symbol for the standard deviation of the sampling distribution of the differences in sample means
Term
 Analysis of Variance
Definition
 A test of significance appropriate for situations in which we are concerened with the differences among more than two sample means.
Term
 ANOVA
Definition
 Analysis of Variance
Term
 F ratio
Definition
 The test statistic computed in step 5 of the ANOVA test
Term
 One-Way Analysis of Variance
Definition
 Applications of ANOVA in which the effect of a single independent variable on a dependent variable is observed.
Term
 Post Hoc Test
Definition
 A technique for determining which pairs of means are significantly different
Term
 Sum of Squares Between (SSB)
Definition
 The sum of the squared deviations of the sample means from the overall mean, weighted by sample size
Term
 Sum of Squares Within (SSW)
Definition
 The sum of the squared deviations of scores from the category means
Term
 Total Sum of Squares (SST)
Definition
 The sum of the squared deviations of teh scores from the overall mean.
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