a set of mathematical procedures for organizing, summarizing and interpreting information
the entire set of the individuals of interest for a particular research question
a set of individuals selected from a population, usually intended to represent the population in a research study
a characteristic or condition that changes or has different values for different individuals
measurements or observations
a collection of measurements or observations
a single measurement or observation, commonly called a score/raw score
a value, usually a numerical value, that describes a population. Usually derived from measurements of the individuals in the population
a value, usually a numerical value, that describes a sample. Usually derived from measurements of the individuals in the sample
statistical procedures used to summarize, organize and simplify data
techniques that allow us to study samples and then make generalization about the populations from which they were selected
the naturally occurring discrepancy, or error, that exists between a sample statistic and the corresponding population parameter
two different variables are observed to determine whether there is a relationship between them
aka correlational research strategy
one variable is manipulated while another variable is observed and measured. To establish a cause-and-effect relationship between the two variables, an experiment attempts to control all other variables to prevent them from influencing the results
whenever a research study allows more than one explanation for the results because it is impossible to reach an unambiguous conclusion
each participant has an equal chance of being assigned to each of the treatment conditions
the variable that is manipulated by the researcher. It usually consists of two (or more) treatment conditions to which subjects are exposed. It consists of antecedent conditions that are manipulated prior to observing the dependent variable
the variable that is observed to assess the effect of the treatment
when individuals do not receive the experimental treatment. Instead, they either receive a neutral, placebo treatment. It provides a baseline for comparison with the experimental condition.
individuals in the control condition
individuals who do receive the experimental treatment. Often called the experimental group.
in a non-experimental study, the "independent" variable that is used to create the different groups of scores
aka hypothetical constructs
internal attributes or characteristics that cannot be directly observed but are useful for describing and explaining behavior
identifies a measurement procedure (a set of operations) for measuring an external behavior and uses the resulting measurements as a definition and a measurement of an internal construct.
It has two components:
1. it describes a set of operations for measuring a construct
2. it defines the construct in terms of the resulting measurements
consists of separate, indivisible categories. No values can exist between two neighboring categories
there are an infinite number of possible values that fall between any two observed values. It is divisible into an infinite number of fractional parts
boundaries of intervals for scores that are represented on a continuous number line.
The real limit separating two adjacent scores is located exactly halfway between the scores.
Each score has two real limits
Upper real limit
This is at the top of the interval
Lower real limit
This is at the bottom of the interval
it consists of a set of categories that have different names.
Measurements on this label and categorize observations, but do not make any quantitative distinctions between observations
it consists of a set of categories that are organized in an ordered sequence.
Measurements on an ordinal scale rank observations in terms of size or magnitude
it consists of ordered categories that are all intervals of exactly the same size.
Equal differences between numbers on the scale reflect equal differences in magnitude.
However, the zero point on this scale is arbitrary and does not indicate a zero amount of the variable being measured
an interval scale with the additional feature of an absolute zero point.
With this scale, ratios of numbers do reflect ratios of magnitude