AP Psychology - Research Methods

Case Study

-A research method used to get a full, detailed picture of one participant or a small group of participants. -For instance, clinical psychologists often use case studies to present information about a person suffering from a particular disorder. -Allows researcher to get the richest possible picture of what they are studying, but the focus on a single individual or small group means that the findings cannot be generalized to a larger population.

Measures of Variability

-A type of descriptive statistical measure that attempts to depict the diversity of the distribution. -Range, variance, and standard deviation are measures of variability. -Range is the distance between the highest and lowest score in a distribution. Variance and standard deviation are closely related; standard deviation is simply the square root of the variance. Both measures essentially relate the average distance of any score in the distribution from the mean.

Inferential Statistics

-Statistics that can determine whether or not findings can be applied to the larger population from which the sample was selected. -Related to the concept of statistical significance: Scientists have decided that 5 percent (0.05) is the cutoff for statistically significant results. This means that in a statistically significant experimental result, there is less than a 5 percent chance that the results occurred by chance.

Participant Bias (also called Response Bias)

-Tendency for subjects to behave in certain ways based on their perception of an experiment. -Can be controlled for using a single-blind procedure (when participants do not know whether they are assigned to an experimental or control group) or a double-blind procedure (when neither the participants nor the researcher are aware of who is in the experimental or control groups while the experiment is going on).

Applied Research

-Research that psychologists conduct to solve practical problems. -Research that has clear, practical applications. -The other category of research is basic research, which explores questions that are of interest to psychologists but are not intended to have immediate, real-world applications.

Statistical Significance

-Scientists have decided that 5 percent (0.05) is the cutoff for statistically significant results. This means that in a statistically significant experimental result, there is less than a 5 percent chance that the results occurred by chance. -Researchers use inferential statistics to determine whether results are statistically significant.

Basic Research

-Research that explores questions that are of interest to psychologists but are not intended to have immediate, real-world applications. -The other category of research is applied research, which is conducted in order to solve practical problems.

Normal Curve

-A bell-shaped curve that represents a distribution of scores that is normally distributed (a few scores at the low end and high end of the distribution, with most of the scores clustered around the mean). -Approximately 68 percent of scores in a normal distribution fall within one standard deviation of the mean, approximately 95 percent of scores fall within two standard deviations of the mean, and almost 99 percent of scores fall within three standard deviations of the mean.

Scatter Plot

-A graph of correlated data. -Graphs pairs of values, one on the y-axis and one on the x-axis. -For instance, the number of hours a group of people study per week could be plotted on the x-axis, while their GPAs could be plotted on the y-axis. The result would be a series of points called a scatter plot. -The closer the points come to falling on a straight line, the stronger the correlation. -A line that slopes upward, from left to right, indicates a positive correlation. A downward slope evidences a negative correlation.

Random Assignment

-A method of assigning participants to conditions such that each participant has an equal chance of being placed into experimental groups. -Assignment is the process by which participants are put into either an experimental or control group. -It limits the effects of confounding variables based on differences between people. -Using random assignment diminishes the chance that participants in the two groups differ in any meaningful way.

Random Selection

-A method of selecting a sample from a population. -Every member of the population has an equal chance of being selected. Random selection increases the likelihood that the sample represents the population and that one can generalize the findings to the larger population.

Stratified Sampling

-A process that allows a researcher to ensure that the sample represents the population on some criteria. -For instance, if a researcher thinks that participants of different racial groups might respond differently, he or she would want to make sure that each race is represented in the sample in the same proportion that it appears in the overall population. In other words, if 500 of the 1,000 students in a school are Caucasian, 300 are African American, and 200 are Latino, in a sample of 100 students the researcher would want to have 50 Caucasians, 30 African Americans, and 20 Latinos.

Hypothesis

-A statement that expresses a relationship between two variables. -In an experimental hypothesis, the dependent variable depends on the independent variable. In other words, a change in the independent variable will produce a change in the dependent variable. -For instance, consider the hypothesis that watching violent television programs makes people more aggressive. In this hypothesis, watching television violence is the independent variable since the hypothesis suggests that a change in television viewing will result in a change in the dependent variable, aggression. -In testing a hypothesis, researcher manipulate the independent variable and measure the dependent variable.

Correlation

-A statistical measure of a relationship between two variables. -Correlation does not imply causation: Just because two variables are correlated does not mean that one variable causes the other. -Can be either positive or negative. A positive correlation between two variables means that the presence of one variable predicts the presences of the other. A negative correlation means that the presence of one variable predicts the absence of the other. -The strength of a correlation is expressed by a number called a correlation coefficient, which ranges from -1 and +1, where -1 is a perfect, negative correlation and +1 is a perfect, positive correlation.

Theory

-Aims to explain some phenomenon and allows researchers to generate testable hypotheses with the hope of collecting data that support the theory. -Hypotheses often grow out of theories.

Operational Definitions

-An explanation of how variables are measured. -Two variables need to be operationally defined in the hypothesis "Watching violent television programs makes people more aggressive": What programs will be considered violent? What behaviors will be considered aggressive?

Confounding Variables

-Any difference between the experimental and control conditions, expect for the independent variable, that might affect the dependent variable. -An experiment allows the researcher to manipulate the independent variable and control for confounding variables.

Hawthorne Effect

-Being selected to be in a group of people to participate in an experiment will affect the performance of that group, regardless of what is done to those individuals. -Just selecting a sample of people and including them in an experiment will affect performance of the sample. -Control groups help to control for the Hawthorne effect.

Reliability

-Good research is both valid and reliable. -Research is reliable when it can be replicated; it is consistent. -If the researcher conducted the same research in the same way, the researcher would get similar results. -A related concept is validity: research is valid when it measures what the researcher set out to measure; it is accurate.

Validity

-Good research is both valid and reliable. -Research is valid when it measures what the researcher set out to measure; it is accurate. -A related concept is reliability: Research is reliable when it can be replicated; it is consistent.

Survey Method

-Involves asking people to fill out surveys. -Often used to gather opinions or attitudes and for correlational research. -Response rate refers to the proportion of a surveyed group who respond to and return a survey.

Double-Blind Procedure

-Method followed such that neither the participants nor the researcher are aware of who is in the experimental or control groups while the experiment is going on. -Double-blind procedures control for both experimenter bias (researchers treating members of the experimental and control groups differently) and participant bias (the tendency for subjects to behave in certain ways based on their perception of an experiment.

Naturalistic Observation

-Research method that involves observing participants in their natural habitats without interacting with them. -The goal is to get a realistic and rich picture of the participants' behavior. -Cannot establish cause and effect relationships between variables.

Hindsight Bias

-Tendency upon hearing about research findings (and many other things) to think that they knew it all along. -After an event occurs, it is relatively easy to explain why it happened. The goal of scientific research, however, is to predict what will happen in advance.

APA Ethical Guidelines for Human Research

-The APA (American Psychological Association) established ethical guidelines for human and animal research. -Any type of academic research must first propose the study to the ethics board or institutional review board (IRK) at the institution. -Guidelines for human research include: Coercion, Informed consent, Anonymity/confidentiality, Lack of risk, Debriefing procedures

APA Ethical Guidelines for Animal Research

-The APA (American Psychological Association) established ethical guidelines for human and animal research. -Ethical psychological studies using animals must meet the following requirements: Have a clear scientific purpose, Care for and house animals in a humane way, Acquire animal subjects legally, Design experimental procedures that employ the least amount of suffering feasible.

Population

-The group from which a sample is selected. -The population includes anyone or anything that could possibly be selected to be in the sample. -The goal in selecting a sample is that it represents a larger population.

Sampling

-The individuals on whom the research is conducted are called participants (or subjects), and the process by which participants are selected is called sampling. -To select a sample (the group of participants), first identify the population from which the sample will be selected. The population includes anyone or anything that could possibly be selected to be in the sample. The goal in selecting a sample is that it represents a larger population. -Random selection means that every member of the population has an equal chance of being selected. Random selection increases the likelihood that the sample represents the population and that one can generalize the findings to the larger population.

Experiment

-The only research method that can show a casual relationship. -Allows the researcher to manipulate the independent variable and control for confounding variables. -A confounding variable is any difference between the experimental and control conditions, expect for the independent variable, that might affect the dependent variable. -Experiments compare at least two groups: an experimental group and a control group that differ based on the independent variable.

Assignment

-The process by which participants are put into either an experimental or a control group. -Random assignment means that each participant has an equal chance of being placed into any group. It limits the effects of confounding variables based on differences between people. -Using random assignment diminishes the chance that participants in the two groups differ in any meaningful way.

Experimenter Bias

-The unconscious tendency for researchers to treat members of the experimental and control groups differently to increase the chance of confirming their hypothesis. -Experimenter bias is not a conscious act. If researchers purposely distort their data, it is called fraud, not experimenter bias. -Using a double-blind procedure can eliminate experimenter bias. A double blind occurs when neither the participants nor the researcher are able to affect the outcome of the research.

Descriptive Statistics

-Ways of describing a set of data. -Measures of central tendency are a common descriptive statistic. -Three common measures of central tendency are the mean, median, and mode. -The mean is the average of all the scores in a distribution. The median is the central score in the distribution. The mode is the score that appears most frequently.