UVA Psych 2005 Research Methods and Data Analysis I

Statistics

branch of mathematics that focuses on the organization, analysis, and interpretation of a group of numbers

Descriptive Statistics

procedures for summarizing a group of scores or otherwise making them more understandable

Inferential Statistics

procedures for drawing conclusions based on the scores collected in a research study but going beyond them

Variable

characteristic that can have different values

Values

possible number or category that a score can have

Score

particular person's value on a variable

Numeric variable

variable whose values are numbers

Equal-interval variable

variable in which the numbers stand for approximately equal amounts of what is being measured

Ratio Scale

an equal-interval variable is measured on a ratio scale if it has an absolute zero point, meaning that the value of zero on the variable indicates a complete absence of the variable (distance, time, weight)

Rank-Order Variable

numeric variable in which the values are ranks, such as class standing or place finished in a race

Nominal Variable

variable with values that are categories (names rather than #s)

Levels of Measurement

types of underlying numerical information provided by a measure, such as equal-interval, rank-order, and nominal

Discrete Variable

variable that has specific values and that cannot have values between these specific values (# of times you went to the dentist)

Continuous Variable

variable for which, in theory, there are an infinite number of values between any two values (age, height, weight, time)

Frequency table

ordered listing of number of individuals having each of the different values for a particular variable

Interval

range of values in a grouped frequency table that are grouped together

Grouped Frequency Table

frequency table in which the number of individuals (frequency) is given for each interval of values

Histogram

barlike graph of a frequency distribution in which the values are plotted along the horizontal axis and the height of each bar is the frequency of that value; the bars are usually placed next to each other without spaces, giving the appearance of a city skyline

Frequency Distribution

pattern of frequencies over the various values; what a frequency table, histogram, or frequency polygon describes

Unimodal Distribution

frequency distribution with one value clearly having a larger frequency than any other

Bimodal Distribution

frequency distribution with two approximately equal frequencies, each clearly larger than any of the others

Multimodal Distribution

frequency distribution with two or more high frequencies separated by a lower frequency; a bimodal distribution is the special case of two high frequencies

Rectangular Distribution

frequency distribution in which all values have approximately the same frequency

Symmetrical Distribution

distribution in which the pattern of frequencies on the left and right side are mirror images of each other

Skewed Distribution

distribution in which the scores pile up on one side of the middle and are spread out on the other side; distribution that is not symmetrical

Floor Effect

situation in which many scores pile up at the low end of a distribution (creating skewness to the right) because it is not possible to have any lower score

Ceiling Effect

situation in which many scores pile up at the high end of a distribution (creating skewness to the left) because it is not possible to have a higher score

Normal Curve

bell-shaped frequency distribution that is symmetrical and unimodal; distributions in nature and in research commonly approximate it

Kurtosis

extent to which a frequency distribution deviates from a normal curve in terms of whether its curve in the middle is more peaked or flat than the normal curve

Assumptions

ideas that are tentatively accepted as being true without further examination

Data

information gathered during research

Facts

empirically observed events

Behaviors

any observable act from an organism

Observation

collecting data about a phenomenon

Inference

any conclusion drawn on the basis of empirical data and/or theories

Inductive Reasoning

reasoning from the particular to the general; used to generate theories based on observations

Deductive reasoning

reasoning from the general to the particular, such as when one makes specific predictions about future events based on theories

Theory

collection of ideas about how and why variables are related

Parsimonious Theory

suggests that a simple theory is preferred over a more complex theory is both theories explain the data equally well

Validity

refers to the methodological and/or conceptual soundness of research

Inductive Theory

built on a strong empirical base and strays little from that base

Intervening variables

Inferred factors hypothesized to operate between observed variables such as a stimulus and response, helping to explain their relationship

Deductive Theory

A theory that emphasizes constructs and the relationship between constructs and seeks to make predictions from the theory that can be tested with empirical research

Functional Theories

emphasize both inductive and deductive elements

Model

a simplified representation of the complex reality of the real world

Phases of Research

the stages of a research project

Idea-Generating Phase

First step in any research project during which the researcher selects a topic to study

Problem-Defining Phase

Research phase in which research ideas are converted into precise questions to be studied, uses deductive reasoning

Procedure-Design Phase

Research phase in which the specific procedures to be used in the gathering and analyzing of data are developed

Observation Phase

research phase in which the data are gathered

Data Analysis Phase

researcher processes the data using statistical procedures

Interpretation Phase

Research phase in which the results are interpreted in light of (1) the adequacy of control procedures, (2) previous research, and (3) existing theories

Communication Phase

research phase in which the rationale, hypotheses, methods, results, and interpretations of the study are presented

Replication

to repeat a study with no changes in the procedure

Levels of constraint

degree of systematic control applied in research

Naturalistic Observation

observing the natural flow of behavior in natural settings

Naturalistic Level of Constraint

research carried out in natural settings, in which the researcher doesn't manipulate the environment

Case Study Research

extensive observations of individuals or small groups, using minimal constraints on behavior

Correlational Research

research that seeks to measure the relationship between variables

Correlational Level of Constraint

Research designed to quantify the relationship between 2 or more variables

Differential Research

Research that involves comparing two or more existing groups

Differential Level of Constraint

Research in which 2 or more groups, defined on the basis of a preexisting variable, are compared on a dependent measure

Preexisting Variable

any characteristic of the individual that existed prior to the research study

Experimental Research

research in which participants are randomly assigned to groups and are compared on at least one dependent measure

Precision-Versus-Relevance Problem

The concern that higher-constraint laboratory research may be less relevant than lower-constraint naturalistic research and, conversely, that lower-constraint research may be unacceptably imprecise.

Central Tendency

typical or most representative value of a group of scores

Mean

arithmetic average of a group of scores

Mode

Value with the greatest frequency in a distribution

Median

Middle score when all the scores in a distribution are arranged from lowest to highest

Outlier

score with an extreme value (very high or very low) in relation to the other scores in the distribution

Variance

measure of how spread out a set of scores are; average of the squared deviations from the mean

Deviation Score

Score minus the mean

Squared Deviation Score

square of the difference between a score and the mean

Sum of Squared Deviations

total of each score's squared difference from the mean

Standard Deviation

square root of the average of the squared deviations from the mean

Computational Formula

equation mathematically equivalent to the definitional formula. Easier to use for figuring by hand, it does not directly show the meaning of the procedure

Definitional Formula

Equation for a statistical procedure directly showing the meaning of the procedure

Independent Variable

Variable that defines groups of participants on the basis of either (1) a preexisting characteristic (non manipulated IV) or (2) random assignment (manipulated IV)

Dependent Variable

variable hypothesized to have a relationship with the IV

Manipulated Independent Variable

Type of IV in which participants are randomly assigned to conditions

Nonmanipulated Independent Variable

the preexisting variable that determines group membership in a differential research study

Causal Relationship

a relationship between variables in which one variable causes a predictable change in the other variable

Extraneous Variables

Any variable, other than the IV, that might affect the dependent measure and thus confound results

Constant

variable that is prevented from varying

Controls

any procedure that reduces confounding

Belmont Report

outlined the basic ethical principles for human research that has been adopted by virtually all research agencies

Deception

procedures used in research to hide the true nature of the study

Concealment

Deliberately misleading participants by withholding some information about the research

Debriefing

disclosing to participants after the study the full nature of a study that used deception

Invasions of privacy

failure of researchers to protect the confidentiality of records

Confidentiality

ethical requirement to protect a participant's sensitive information

Informed Consent

principle that participants have the right to know exactly what they are getting into before they agree to participate in a research study

Institutional Review Board (IRB)

formal body that reviews research proposals to determine if they meet ethical guidelines

Risk/Benefit Analysis

assessing research in terms of the risks it poses to participants, its value to science and society, and whether potential benefits outweigh those risks

Ethical Checks

a series of questions about the research procedures designed to identify and correct potential ethical problems

Diversity

how well various ethnic, cultural, age, and gender groups are represented in a research sample

Laboratory Animal Care Committee

Committee that reviews the ethics of research proposals involving animals

Z Score

number of standard deviations that a score is above (or below, if it is negative) the mean of its distribution; it is thus an ordinary score transformed so that it better describes the score's location in a distribution

Raw Score

ordinary score (or any number in a distribution before it has been made into a Z score or otherwise transformed)

Normal Distribution

frequency distribution that follows a normal curve