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Psychology Statistics
Descriptive Statistics - Procedures for summarizing a group of scores or otherwise making them more understandable (Concerns only the data that you actually collected or only your sample) Inferential Statistics - Draw conclusions/make inferences that go beyond the scores from a research study. Generalizing the sample you collected to a larger population that was not measured. Variable - A characteristic that can have different values (anything that can "vary") Value - A possible number or category that a score can have Score - A particular person's value on a person. Independent Variable - The variable that is varied or manipulated by the researcher. Dependent Variable - The outcome variable, or the variable we are interested in measuring, variable the experimenter measures. Quantitative Variable - Numeric, (ie. Age, Hours per week watching television)
Categorical Variables - Gender, Religious Affiliation, etc. Discrete Variables - Variable that has specific values and that cannot have values between these specific values. (grades on exam) Continuous Variables - variables for which in theory there are infinite number of values between any two values. (Age, time spent studying) Nominal Variable - variable with values that are categories (that is they are names rather than numbers) and can also be called categorical variable Ordinal (rank-order) variable - numeric variable in which the values are ranks, such as class standing or place finished in a race. Interval (Equal-Interval) variable - variable in which the numbers stand for approximately equal amounts of what is being measured. Interval Scale - ordinal variable where the distance between the attributes, or categories, does have meaning. The spacing between value is of equal distance Ratio Scale - An interval variable where the value of zero does have the meaning of an absence of the thing being measured, no numbers exist below zero. (example: weight) Unimodal Distribution -
Each distribution extends from ______ standard deviations. A Z-score always has a mean of - 0 A Z-score also always has a SD of? - 1 When referring to samples we use _____ letters - Roman When referring to populations we use ______ letters - Greek Sample Statistics - these are computed from known information Population Parameters - these are estimated based on sample statistics We usually do not know the exact.... Probability - expected relative frequency of an outcome; the proportion of successful outcomes to all outcomes. Expected relative frequency - How often something happens compared to how many times it might have happened, in the long run. Probability. -
Calculated by dividing the number of possible successful outcomes, by all possible outcomes. Proportion - Range of probability always in decimal form. Level of Significance - Also referred to as the alpha level Hypothesis testing - is a procedure for testing a claim about a property of a population. Hypothesis - A _________ is a claim or statement about a property of a population Null - The claim being tested in a significance test is the _____ hypothesis. Null; Research/Alternative - A test of significance looks for evidence against the _____ hypothesis and in favor of the _______ hypothesis. test statistic - The ______ is a value used in making a decision about the null hypothesis. It is found by converting the sample statistic (such as the mean, M) to a score (such as z or t) with the assumption that the null hypothesis is true. null hypothesis - The _______ is a statement that the value of a population parameter (such as the mean) is equal to some claimed value. It is assumed to be true and a conclusion is reached to either reject or fail to reject it.
