Statistics
A set of mathematical procedures for organizing, summarizing, and interpreting information.
Population
The set of all the individuals of interest in a particular study.
Sample
A set of individuals selected from a population, usually intended to represent the population in a research study.
Data (plural)
Measurements or observations
Parameter (Population)
A value, usually numerical, that describes a population. Usually derived from the measurements of the individuals in the population.
Statistic (sample)
A value, usually numerical, that describes a sample. Usually derived from the measurements of the individuals in a sample.
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 derived.
Sampling Error
The discrepancy (or amount of error) that exists between a sample statistic and the corresponding population parameter.
A researcher is interested in the rading skill of fourth-grade students in the state of Texas. the average reading score for the entire goup of fourth-grade students would be an example of a _______?
Parameter.
A researcher is interested in the effect of watching a reality television show about modeling on the eating behavior of 13-year-old girls. A group of 30 13-year-old girls is selected to participate in a research study. The group of 30 13-year-old girls is
Sample.
In the study of the effect of modeling shows on teen eating behaviours, the amount of food eaten in one day is measured for each girl and the researcher computes the average score for the 30 13-year-olds. The average score is an example of a _______?
Statistic.
Correlational Method
Two different variables are observed to determine whether there is a relationship between them.
Experimental Method
One variable is MANIPULATED, while another variable is observed and measured.
Independent Variable
Variable that is manipulated by the researcher, usually consisting of the two (or more) treatment conditions to which subjects are exposed. (Antecedent conditions that were manipulated prior to observing the dependent variable).
Constructs
internal attributes (such as intelligence, anxiety, and hunger) that cannot be directly observed but are useful for describing and explaining behavior. Intangible; Cannot be directly observed.
Operational definition
Identifies a measurement procedure for measuring for measuring external behavior, using the resulting measurements as a definition and a measurement of a hypothetical construct. Ex - intelligence is measured and defined by performance on an IQ test.
Continuous (interval, ratio) variable
Consists of an infinite number of possible values that fall between any two observed values (fractions & decimals). EX - test score, reaction time, weight
Real Limits
Boundaries of intervals for scores that are represented on a continuous number line (located exactly halfway between the scores, thus having two limits (upper limit, lower limit). Ex - time of 31.1 seconds = upper 31.15, lower 31.05.
Nominal Scale
A set of categories that have different names - categorized but not quantified distinctions between observations. Ex - Academic Majors, sports teams, meal preference, religion
Ordinal Scale
A set of categories that are organized in an ordered sequence (names and fixed order) ranked by size or magnitude. Ex - 1st, 2nd, 3rd, or small, medium, large.
Interval Scale
Arbitrary value for zero; Consists of ordered categories that are all intervals of exactly the same size with equal differences between numbers representing equal differences in magnitude. Ex - Temperature
Ratio Scale
Zero is representative of none or complete absence; determines direction and size of difference. Ex - height, weight, reaction time, test errors.
Discrete variable
A variable in which the units are in the whole numbers, or "discrete" units (for example, number of children, number of defects).