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Psychology Statistics Chapter 1
population - the set of all the individuals of interest in a particular study sample - a set of individuals selected from a populatio, usually intended to represent the population in a research study variable - a characteristic or condition that changes or has different values for different individuals data - measurements or observations data set - a collection of measurements or observations datum - a single measurement or observation, aka score or raw score parameter - a numerical value that describes a population, usually derived from measurements of the individuals in the population statistic - a numerical value that describes a sample, usually derived from measurements of the individuals in the sample
2 categories of statistical procedures - descriptive and inferential descriptive statistics - statistical procedures used to summarize, organize, and simplify data inferential statistics - techniques that allow us to study samples and then make generalizations about the populations from which they were selected sampling error - the discrepancy, or amount of error, that exists between a sample statistic and a corresponding population parameter correlational method - two different variables are observed to determine whether there is a relationship between them experimental method - compares groups of scores to demonstrate a cause-and-effect relationship between two variables manipulation - change the value of one variable from one level to another, then a second variable is measure to determine whether the manipulation causes changes to occur control (in the experimental method) - researcher must exercise control over the research situation to ensure that other variables do not influence the relationship being examined participant variables -
experimental condition - individuals do receive the experimental treatment quasi-independent variable - in a nonexperimental study, this variable is used to create the different groups of scores constructs - internal attributes or characteristics that cannot be directly observed but are useful for describing and explaining behavior operational definition - identifies a measurement procedure for measuring an external behavior and uses the resulting measurements as a definition and a measurement of a hyppothetical construct 2 components of an operational definition -
- describes a set of operations for measuring a construct
- defines the construct in terms of the resulting measurements discrete variable - separate indivisible categories with no intermediate values between the two adjacent categories continuous variable - an infinite number of possible values that fall between two observed values, can be divided into an infinite number of fractional parts real limits - the boundaries of intervals for scores that are represented on a continuous number line, located exactly halfway between the upper and lower limits
nominal scale - a set of categories that have different names, measurements on this scale label and categorize observations, but do not make an quantitative distinctions between observations ordinal scale - a set of categories that are organized in an ordered sequence, measurements on this scale rank observations in terms of size or magnitude interval scale - ordered categories with intervals of the same size, a zero is arbitrary and does not indicate a zero amount of the variable being measured ratio scale - an interval scale with an absolute zero point, ratios of numbers do not reflect ratios of magnitude pre-post study - measures two scores for each individual, measuring before and after therapy
