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Chapter 1
Intro to Statistics
The term statistics refers to a set of…
Chapter 1
Intro to Statistics
The term statistics refers to a set of mathematical procedures for organizing, summarizing, and interpreting information.
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Sample
A sample is a set of individuals selected from a population, usually intended to represent the population in a research study.
Variables
A variable is a characteristic or condition that changes or has different values for different individuals.
Variables
Experimental
In the experimental method, 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.
Independant
The independent variable is the variable that is manipulated by the researcher. In behavioral research, the independent variable usually consists of the two (or more) treatment conditions to which subjects are exposed. The independent variable consists of the antecedent conditions that were manipulated prior to observing the dependent variable.
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Control Condition
Individuals in a control condition do not receive the experimental treatment. Instead, they either receive no treatment or they receive a neutral, placebo treatment. The purpose of a control condition is to provide a baseline for comparison with the experimental condition.
Experimental Condition
Individuals in the experimental condition do receive the experimental treatment.
Correlational
In the correlational method, two different variables are observed to determine whether there is a relationship between them.
Non-experimental
A nonexperimental study does not permit a cause-and effect explanation. We can say that changes in one variable are accompanied by changes in a second variable, but we cannot say why.
nonequivalent groups
A research study in which the different groups of participants are formed under circumstances that do not permit the researcher to control the assignment of individuals to groups and the groups of participants are, therefore, considered nonequivalent.
pre–post study
Quasi-experimental and nonexperimental designs consisting of a series of observations made over time. The goal is to evaluate the effect of an intervening treatment or event by comparing observations made before versus after the treatment.
A discrete variable consists of separate, indivisible categories. No values can exist between two neighboring categories.
For a continuous variable, there are an infinite number of possible values that fall between any two observed values. A continuous variable is divisible into an infinite number of fractional parts.
An operational definition 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 a hypothetical construct.
Constructs are internal attributes or characteristics that cannot be directly observed but are useful for describing and explaining behavior.
Parameters
A parameter is a value, usually a numerical value, that describes a population. A parameter is usually derived from measurements of the individuals in the population.
Data
Data (plural) are measurements or observations. A data set is a collection of measurements or observations. A datum (singular) is a single measurement or observation and is commonly called a score or raw score.
Scales of Measurement
A nominal scale consists of a set of categories that have different names. Measurements on a nominal scale label and categorize observations, but do not make any quantitative distinctions between observations.
An ordinal scale 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.
An interval scale consists of ordered categories that are all intervals of exactly the same size. Equal differences between numbers on scale reflect equal differences in magnitude. However, the zero point on an interval scale is arbitrary and does not indicate a zero amount of the variable being measured.
A ratio scale is an interval scale with the additional feature of an absolute zero point. With a ratio scale, ratios of numbers do reflect ratios of magnitude.
Statistics
A statistic is a value, usually a numerical value, that describes a sample. A statistic is usually derived from measurements of the individuals in the sample.
Sampling Error
Sampling error is the naturally occurring discrepancy, or error, that exists between a sample statistic and the corresponding population parameter.
Descriptive Statistics
Descriptive statistics are statistical procedures used to summarize, organize, and simplify data.
Inferential Statistics
Inferential statistics consist of techniques that allow us to study samples and then make generalizations about the populations from which they were selected.
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Real limits are the 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. The upper real limit is at the top of the interval, and the lower real limit is at the bottom.
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Resource:
Gravetter, F.J. & Wallnau, L.G. (2017). Statistics for the Behavioral Sciences (10th edition) by Wadsworth, Cengage Brain (1 term Printed : MindTap Access Card, ISBN 9781305647312).
