What is a 95 percent confidence interval? most common statistical standardReference page(s): 140 What is a census? Researchers who enjoy complete access to their populations of interest are working with a census (as opposed to a sample).Reference page(s): 123 What is the central limit theorem? For random sampling with a large sample size n, the sampling distribution of the sample mean y is approximately a normal distribution. This holds no matter what the shape of the population distribution. The result also applies to proportions.Reference page(s): 137 What are degrees of freedom? the number of independent observations used to calculate a statisticReference page(s): 145

 What are inferential statistics? Provide predictions about a population, based on data from a sample of that population.Reference page(s): 122 What are the mean and standard error of y? Consider a random sample of size n from a population having mean μ and standard error σ. The sampling distribution of y gives the probabilities for the possible values of y. It has mean μ and standard error σy = σ/sqrt(n). What is the mean of a probability distribution? The expected value of a realization of the distribution, E(y). For a discrete variable, the mean, μ = ΣyP(y). What is the normal distribution? a distribution defined by a mathematical formula and the graph of which has a symmetrical, bell shape; in which the mean, mode, and median coincide; and in which a fixed proportion of observations lies between the mean and any distance from the mean measured in terms of the standard deviationReference page(s): 137

 What is the normal distribution? A symmetric, bell shaped distribution characterized by its mean, μ, and standard deviation, σ. The probability within any particular number of standard deviations of μ is the same for all normal distributions. This probability equals 0.68 within 1 standard deviation, .095 within 2 standard deviations, and 0.997 within 3 standard deviations. What is a population? all the cases or observations covered by a hypothesis; all the units of analysis to which a hypothesis appliesReference page(s): 123 What is a population parameter? the incidence of a characteristic or an attribute in a population (not a sample)Reference page(s): 123 What is probability? With a random sample or randomized experiment, the probability an observation has a particular outcome is the proportion of times that outcome would occur in a very long sequence of observations.Reference page(s): 139

 What is a random sample? A set of observations randomly drawn from the population of interest. Random selection ensures the sample is representative of the population of interest.Reference page(s): 124 What is random sampling error? extent to which a sample statistic differs BY CHANCE from a population parameterReference page(s): 126 What is random selection? Random selection occurs when every member of the population has an equal chance of being included in the sample.Reference page(s): 125 Define range. the distance between the highest and lowest values or the range of categories into which observations fallReference page(s): 131

 What is response bias? Response bias occurs when the subject gives an incorrect response (perhaps lying), or the question wording or the way the researcher asks a question is confusing or misleading.Reference page(s): 125 What is a sample? a subset of observations or cases drawn from a specified populationReference page(s): 123 What is a sample proportion? the number of cases falling into one category of the variable divided by the number of cases in the sampleReference page(s): 148 What is a sample statistic? the estimator of a population characteristic or attribute that is calculated from sample dataReference page(s): 123

 What is a sampling distribution? The probability distribution that specifies probabilities for the possible values the statistic can take. What is a sampling frame? The population from which a sample is drawn. Ideally it is the same as the total population of interest to a study.Reference page(s): 124 What is selection bias? Selection bias occurs when non-random processes - often unknown to the researcher - cause differences between test (treatment) group and the control group.Reference page(s): 124 What is a standard deviation? A measure of dispersion of data points about the mean for interval- and ratio-level data. Standard deviation is equal to the square root of variance, and describes a typical distance from the mean.Reference page(s): 129

 What is a standard error? The standard deviation of the sample distribution of y is called the standard error of y. The standard error of y is denoted by σy.Reference page(s): 135 What is a standard error? The standard deviation of the sample distribution of y is called the standard error of y. The standard error of y is denoted by σy. What is the standard normal distribution? The normal distribution with mean μ = 0 and standard deviation σ = 1. What is standardization? occurs when the numbers in a distribution are transformed into standard units of deviation from the mean of the distributionReference page(s): 137

 What is the Student's t-distribution? a probability distribution that can be used to make inferences about a population mean when the sample size is smallReference page(s): 144 What is variance? A measure of dispersion of data points about the mean for interval- and ratio-level data. Variance averages the squared deviations about the mean.Reference page(s): 132 What is a Z score? the number of standard deviations by which a score deviates from the mean scoreReference page(s): 138