CED Section 1 - Scientific Method

Experimental vs. non-experimental

An experiment is any study in which a treatment is introduced. A new method of teaching.

A non-experimental study does not introduce a treatment.

Comparing opinions from natural groups.

Independent Variable (IV)

the factor the researcher manipulates in a controlled experiment (the cause)

Dependent Variable (DV)

The measured outcome of a study; the responses of the subjects in a study.

Confounding Variables

a factor other than the independent variable that might produce an effect in an experiment; not variables about the subjects - those are controlled for by random assignment

Random assignment

assigning participants to experimental and control conditions by chance, thus minimizing preexisting differences between those assigned to the different groups

population

the whole group that you want to study and describe

sample

A relatively small proportion of people who are chosen in a survey/experiment so as to be representative of the whole.

random sampling

a sample that fairly represents a population because each member has an equal chance of inclusion

representative samples

Better than biased samples.

Random groups selected.

A sample that is similar to the population as a whole in regard to variables that might impact the results such as gender, religious affiliation, income, and ethnicity.

convenience samples

samples of individuals who are the most readily available; not as good as representative samples

sampling bias

a flawed sampling process that produces an unrepresentative sample

generalizability

the extent to which we can claim our findings inform us about a group larger than the one we studied

experimental group

In an experiment, the group that is exposed to the treatment, that is, to one version of the independent variable.

control group

In an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.

placebo group

A control group of participants who believe they are receiving treatment, but who are only receiving a placebo.

placebo effect

experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent.

single-blind procedure

research design in which participants don't know whether they are in the experimental or control group

double-blind procedure

an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Eliminates experimenter bias.

experimenter bias

a phenomenon that occurs when a researcher's expectations or preferences about the outcome of a study influence the results obtained

case study

an observation technique in which one person is studied in depth in the hope of revealing universal principles; the research method the most prone to bias

correlation

A measure of the extent to which two factors vary together, and thus of how well either factor predicts the other; cause and effect cannot be deterimined from a correlation

positive correlation

A correlation where as one variable increases, the other also increases, or as one decreases so does the other. Both variables move in the same direction.

negative correlation

as one variable increases, the other decreases

directionality problem

a problem encountered in correlational studies; the researchers find a relationship between two variables, but they cannot determine which variable may have caused changes in the other variable

third-variable problem

the concept that a correlation between two variables may stem from both being influenced by some third variable

scatterplot

a graphical depiction of the relationship between two variables; used with correlations

correlation coefficient

a statistical index of the relationship between two things (r= -1 to +1)

quantitative measures

units of measure expressed in numerical terms

Likert Scale

a numerical scale used to assess attitudes; includes a set of possible answers with labeled anchors on each extreme; example: 5=strongly agree, 4=agree, etc.

Qualitative measures

Data not recorded in numerical form (example, open ended answers from an interview)

structured interviews

interviews in which all applicants are asked the same set of standardized questions, usually including situational, behavioral, background, and job-knowledge questions

surveys

Questionnaires and interviews that ask people directly about their experiences, attitudes, or opinions.

framing

the way an issue is posed; how an issue is framed can significantly affect decisions and judgments.

social desirability bias

A tendency to give socially approved answers to questions about oneself.

self-report bias

systematic errors that can occur in self-report data because participants are unable or unwilling to answer accurately

meta-analysis

a procedure for statistically combining the results of many different research studies

naturalistic observation

observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation

hypothesis

A testable prediction, often implied by a theory

falsifiability

a feature of a scientific theory, in which it is possible to collect data that will prove the theory wrong

operational definitions

a statement of the procedures used to define research variables

replication

repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding extends to other participants and circumstances

peer review

A process by which the procedures and results of an experiment are evaluated by other scientists who are in the same field or who are conducting similar research.

ethical guidelines

informed consent/assent, do no harm, confidentiality, debriefing, IRB approval

Institutional Review Board (IRB)

A committee at each institution where research is conducted to review every experiment for ethics and methodology.

informed consent

an ethical principle that research participants be told enough to enable them to choose whether they wish to participate

informed assent

Agreement by a minor or other not able to give legal consent to participate in the activity.

protection from harm

the right of research participants to be protected from physical or psychological harm

confidentiality

the act of holding information in confidence, not to be released to unauthorized individuals

minimal deception

Sometimes it is necessary to conduct research without participants knowing the true purpose of the study. Deception can only be used if it is minimal, will not cause lasting harm and is absolutely necessary.

confederates

in psychological and social research, a confederate is a person who is working with the experimenter and posing as a part of the experiment, but the subjects are not aware of this affiliation

debriefing

the post-experimental explanation of a study, including its purpose and any deceptions, to its participants

central tendency

mean, median, mode

mean

average

Mode

the most frequently occurring score(s) in a distribution

median

the middle score in a distribution; half the scores are above it and half are below it; put in ascending order first (include duplicates), find the middle score; if it's an even distribution take the average of the two middle scores

range

the difference between the highest and lowest scores in a distribution

standard deviation

a computed measure of how much scores vary around the mean score

normal curve (normal distribution)

a symmetrical, bell-shaped curve that describes the distribution of many types of data; most scores fall near the mean (about 68 percent fall within one standard deviation of it) and fewer and fewer near the extremes.

Positive skewed distribution

Most of the scores are bunched towards the left. More low scores than high.

negative skewed distribution

Most of the scores are bunched towards the right. More high scores than low.

one standard deviation

68%

two standard deviations

95%

three standard deviations

99.7%

bimodal distributions

frequency distribution in which there are two high points rather than one

regression toward the mean

the tendency for extreme or unusual scores to fall back (regress) toward their average.

statistical significance

a statistical statement of how likely it is that an obtained result occurred by chance (p<.05)

effect size

the magnitude, or strength, of a relationship between two or more variables

confirmation bias

a tendency to search for information that supports our preconceptions and to ignore or distort contradictory evidence

hindsight bias

the tendency to believe, after learning an outcome, that one would have foreseen it

overconfidence

the tendency to be more confident than correct—to overestimate the accuracy of our beliefs and judgments.

Nature vs. Nurture

name for a controversy in which it is debated whether genetics or environment is responsible for driving behavior

genetic predisposition

inborn tendencies

evolutionary perspective

the theory that seeks to identify behavior that is a result of our genetic inheritance from our ancestors

eugenics

the science of improving a human population by controlled breeding to increase the occurrence of desirable heritable characteristics

twin studies

a common method of investigating whether nature or nurture affects behavior