2.6 AP Psych

perfect correlation

+1.00 or -1.00

causation

A cause and effect relationship in which one variable controls the changes in another variable.

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.

within subjects design

An experiment in which the same subjects are assigned to each group. Also called repeated measures design.

between subjects design

Each participant experiences only one level of the independent variable

Do correlations help us predict the future?

In a way

Ms. Ledbetter wants to determine if the new review activity she developed will improve student performance on unit exams. She randomly separates 160 students into two groups. Group A reviews for the unit exam in the traditional manner they have always used. Group B participates in the new review activity. After reviewing, both groups are given the same unit exam and their scores are compared. Identify the independent and dependent variables for this experiment.

The independent variage is the form of review and the dependent variable is their scores.

Students with higher scores on anxiety scales were found to have lower scores on standardized tests. What research method would show this relationship? Why can no cause-effect conclusion be drawn from the results?

This research method is a correlation study. There are three possibilities for causation: Anxiety could cause low test scores, low test scores could cause anxiety, or a third factor could cause both anxiety and low test scores. No conclusions can be drawn about causation because this is not an experiment.

what happens if you have an experimental group but no control group? How do you rectify that?

You test the people twice at different times, comparing the subject to the subject. This is called a within subjects design

Which of the following is an example of negative correlation?(a) People who spend more time exercising tend to weigh less. (b) Teenage females tend to have fewer speeding tickets than teenage males. (c) Students with low IQ scores tend to have lower grades. (d) As hours studying for a test decrease, so do grades on that test. (e) Students' shoe sizes are not related to their grades.

a

confounding variable

a factor other than the independent variable that might produce an effect in an experiement

scatterplot

a graphed cluster of dots, each which represents the values of two variables. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation (little scatter indicates high correlation)

correlation

a measure of the extent to which two variables change together, and thus of how well either variable predicts the other

inverse correlation

a relationship between two variables where as one increases, the other decreases

experiement

a research method in which an investigator manipulates one or more factors (independent cariables) to observe the effect on some behavior or mental process (the dependent variable). By random assignment of participants, the experienmenter aims to control other relevant variables

correlation coefficient

a statistical index of the relationship between two variables (from -1.0 to +1.0)

double-blind procedure

an experiemental procedure in which both the research participants and the reserach staff are ignorant (blind) about whether the research paricipants have recieved the treatment or placebo. Commonly used in drug-evaluation studies

random assignment

assigning participants to experimental and control groups by chance, thus minimizing preexcisting differences between different groups

The purpose of random assignment is to (a) allow participants in both the experimental and control groups to be exposed to the independent variable. (b) ensure that every member of the population had an equal chance of being selected to participate in the research. (e) eliminate the placebo effect. d. reduce potential confounding variables. (e) generate operational definitions for the independent and dependent variables

b

If you are measuring something that is already there is it correlational or experimental?

correlational, because in experiments you manipulate the subjects into independent variables

Which of the following correlation coefficients represents the strongest relationship between two variables? (a) +.30 (b) +.75 (c) +1.3 (d) -.85 (e) -1.2

d

Which of the following is used only in correlation studies? (a) Double blind (b) Placebo (c) Random assignment (d) Scatterplot (e) Random sample

d

Weakest of the three categories?

descriptive- surveys, case studies, naturalistic observation

correlational research method

detects naturally occuring relationships and how they predict eachother. No manipulation, two or more variables. Large groups, makes situation ethical, but does not specify cause and effect

placebo effect

experiemental results caused by expecations alonel any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent

Best form of study? (of the types like correlational, experiemental, etc.)

experimental; you control and manipulate subjects and variable

experiemental research method

explores causes and effects, manipulates one or more variables (independent variables), specifies cause and effect, sometimes not ethical to manipulation to an extent and can be impossible to conduct

experiemental group

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

control group

in an experiment, the group not exposed to the treatment, contrasts with the experimental group and serves as a comparison for evaluation the effect of treatment

where are independent and dependent variables found?

in experimental studies only

Researchers have discovered that individuals with lower income levels report having fewer hours of total sleep. Therefore,

income and sleep levels are positively correlated.

correlation is not causation

just because two variables correlate strongly does not mean that one caused the other

descriptive research method

observes and record behaviors, does case studies, naturalistic observation or surveys. Hard to determine cause and effect, case studies are ethical, but can be misleading

random assignment vs. random sample

random sample is part of the population, random assignment is making sure those in the samples are randomly assigned to groups

independent variable

the experiemental factor that is manipulated; the variable whose effect is being studied

validity

the extent to which a test or experiement measures or predicts what it is supposed to

dependent variable

the outcome factor, the variable that may change in response to manipulations of the independent variable

illusionary correlation

the perception of a relationship where none exists

negative correlation

the relationship between two sets of data, in which one set of data decreases as the other set of data increases.