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50 Cards in this Set
 Front
 Back
Normal Distribution

A bellshaped and symmetrical theoretical distribution with the mean, median, and mode all coinciding at its peak and with the frequencies gradually decreasing at both ends of the curve.


Standard Normal Distribution

A normal distribution represented in standard (Z) scores.


Standard Normal Table

A table showing the area (as a proportion, which can be translated into a percentage) under the standard normal curve corresponding to any Z score or its fraction.


Standard (Z) Score

The number of standard deviations that a given raw score is above or below the mean.


Population

A group that includes all the cases (individuals, objects, or groups) in which the researcher is interested.


Sample

A relatively small subset selected from a population.


Parameter

A measure (for example, mean or standard deviation) used to describe the population distribution.


Statistic

A measure (for example, mean or standard deviation) used to describe the sample distribution.


Probability Sampling

A method of sampling that enables the researcher to specify for each case in the population the probability of its inclusion in the sample.


Simple Random Sample

A sample designed in such a way as to ensure that (1) every member of the population has an equal chance of being chosen and (2) every combination of N members has an equal chance of being chosen.


Systematic Random Sampling

A method of sampling in which every Kth member in the total population is chosen for inclusion in the sample after the first member of the sample is selected at random from among the first K members in the population


Stratified Random Sample

A method of sampling obtained by (1) dividing the population into subgroups based on one or more variables central to our analysis and (2) then drawing a simple random sample from each of the subgroups.


Proportionate Stratified Sample

The size of the sample selected from each subgroup is proportional to the size of that subgroup in the entire population.


Disproportionate Stratified Sample

The size of the sample selected from each subgroup is disproportional to the size of that subgroup in the population.


Sampling Error

The discrepancy between a sample estimate of a population parameter and the real population parameter.


Sampling Distribution of the Mean

A theoretical probability distribution of sample means that would be obtained by drawing from the population all possible samples of the same size.


Standard Error of the Mean

The standard deviation of the sampling distribution of the mean. It describes how much dispersion there is in the sampling distribution of the Mean.


Central Limit Theorem

If all possible samples of size N are drawn from a population with mean muy and standard deviation sigmay, then as N becomes larger, the sampling distribution of sample means becomes approximately normal.


Estimation

A process whereby we select a random sample from a population and use a sample statistic to estimate a population parameter.


Point Estimate

A sample statistic used to estimate the exact value of a population parameter.


Confidence Interval (Interval Estimate)

A range of values defined by the confidence level within which the population parameter is estimated to fall.


Confidence Level

The likelihood, expressed as a percentage or a probability, that a specified interval will contain the population parameter.


Statistical Hypothesis Testing

A procedure that allows us to evaluate hypotheses about population parameters based on sample statistics.


Research Hypothesis

A statement reflect the substantive hypothesis. It is always expressed in terms of population parameters, but its specific form varies from test to test.


Null Hypothesis

A statement of "no difference" that contradicts the research hypothesis and is always expressed in terms of population parameters.


OneTailed Test

A type of hypothesis test that involves a directional hypothesis. It specifies that the values of one group are either larger or smaller than some specified population value.


TwoTailed Test

A type of hypothesis test that involves a nondirectional research hypothesis.


Z Statistic (Obtained)

The test statistic computed by converting a sample statistic (such as a mean) to a Z score.


P Value

The probability associated with the obtained value of Z.


Alpha

The level of probability at which the null hypothesis is rejected.


Type I Error

The probability associated with rejecting a null hypothesis when it is true.


Type II Error

The probability associated with failing to reject a null hypothesis when it is false.


T Statistic (Obtained)

The test statistic computed to test the null hypothesis about a population mean when the population standard deviation is unknown and estimated using the sample standard deviation.


T Distribution

A family of curves each determined by its degrees of freedom.


Degrees of Freedom

The number of scores that are free to vary in calculating a statistic.


Sampling Distribution of the Difference Between Means

A theoretical probability distribution that would be obtained by calculating all the possible mean differences that would be obtained by drawing all the possible independent random samples from two populations.


ChiSquare Test

An inferential statistics technique designed to test for significant relationships between two variables organized in a bivariate table.


Independence (statistical)

The absence of association between two crosstabulated variables. The percentage distributions of the dependent variable within each category of the independent variable are identical.


Expected Frequencies

The cell frequencies that would be expected in a bivariate table if the two variables were statistically independent.


Observed Frequencies

The cell frequencies actually observed in a bivariate table.


ChiSquare (obtained)

The test statistic that summarizes the differences between the observed and expected frequencies in a bivariate table.


Analysis of Variance (ANOVA)

An inferential statistic technique designed to test for a significant relationship between two variables in two or more samples.


BetweenGroup Sum of Squares

Measure of the difference between groups. The amount of variation in the dependent variable that can be attributed to or explained by the independent variable.


Mean Square Within

The withingroup variance.


OneWay ANOVA

ANOVA procedures applied to data with one dependent and one independent variable.


F Obtained

The calculated statistic.


F Ratio or F Statistic

The ratio of betweengroup variance to withingroup variance.


Mean Square Between

An estimate of the betweengroup variance.


Total Sum of Squares

The amount of total variation in scores.


WithinGroup Sum of Squares

Measure of the variation of scores within a single sample. The amount of unexplained variance.
