Chapter 1 Flashcards
statistics (term)
refers to a mathematical set of 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.
The relationship between a population and a sample.
a researcher studies a sample and then generalizes the results from the sample to the population.
Variable
a characteristic or condition that changes or has different values for different individuals.
Datum
(singular) is a single measurement or observation and is commonly called a score or raw score.
Data
(plural) are measurements or observations.
Parameter
a value, usually a numerical value, that describes a population. A parameter is usually derived from measurements of the individuals in the population.
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.
Descriptive Statistics
statistical procedures used to summarize, organize, and simplify data.
inferential statistics
consist of techniques that allow us to study samples and then make generalizations about the populations from which they were selected.
sampling error
is the naturally occurring discrepancy, or error, that exists between a sample statistic and the corresponding population parameter.
Sampling error example
Because the characteristics of each sample depend on the specific people in the sample, statistics will vary from one sample to another. For example, the five students in sample 1 have an average age of 19.8 years and the students in sample 2 have an average age of 20.4 years.
Relationships between Variables
Most research, however, is intended to examine relationships between two or more variables.
correlational method
two different variables are observed to determine whether there is a relationship between them.
Chi-square tests
summary tables
scatter plot
a graph in which each individual is represented by a point so that the horizontal position corresponds to the student’s wake-up time and the vertical position corresponds to the student’s academic performance score.
Limitations of the Correlational Method
The results from a correlational study can demonstrate the existence of a relationship between two variables, but they do not provide an explanation for the relationship.We can say that changes in one variable are accompanied by changes in a second variable, but we cannot say why.
experimental method/experimental 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.
Manipulation
The researcher manipulates one variable by changing its value from one level to another
Control
The researcher must exercise control over the research situation to ensure that other, extraneous variables do not influence the relationship being examined.
When using the experimental method to correlate two or more manipulated and controlled variables, what are two general categories of variables that researchers must consider?
Participant variables
environmental variables
Three basic techniques to control other variable
random assignment, matching, holding them constant
*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.
*Dependent Variable
the variable that is observed to assess the effect of the treatment.
Correlational method vs Experimental method
In a correlational methods, both or more variables are measured. In experimental methods, one or more variable is controlled and manipulated (independent) while only one variable is observed (dependent).
Control condition
An individual does 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 comparison with the experimental condition.
experimental condition
Individuals who receive the experimental treatment.
Non-experimental study
A study that does not have control and experimental groups.
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.
quasi-independent variable.
the “independent variable” (considered but not really) that is used to create the different groups of scores
discrete variable
variables that are counted (how many marbles) A discrete variable consists of separate, indivisible categories. No values can exist between two neighboring categories.
continuous variable
variables that are measured (height inches) 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.
Constructs
internal attributes or characteristics that cannot be directly observed but are useful for describing and explaining behavior.
Nonequivalent group study
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.
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.
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. Note that an operational definition has two components. First, it describes a set of operations for measuring a construct. Second, it defines the construct in terms of the resulting measurements.
