AP Psych Barron's Chapter 2 Methods Notes

Chapter 2 Methods

Research Methods

- More likely to see a FRQ on this topic (research methods) than on any other.

- Psychologists conduct research in order to solve practical problems.

o I.e. find out which method of teaching children is better.

o This type of research is known as applied research as it has a clear, practical application.

- Other psychologists conduct basic research

o Explores questions that are of interest to psychologists but are not intended to have immediate RL applications.

§ Incl. how people form their attitudes about others, how people define intelligence.

Terminology

- Good research is both valid and reliable

o Valid is when it measures what the researcher set out to measure; I t is accurate

o Reliable when it can be replicated, is consistent.

- Hypothesis and variables

o Hypothesis expresses relationship between two variables

o Variables are things that can vary among participants in research.

§ Religion, stress level, height are variables.

§ Where dependent variable depends on the independent variable.

- When testing a hypothesis, researchers manipulate the independent variable and measure the dependent variable.

o Hypotheses often grow out of theories, which aims to explain some phenomenon and allows researchers to generate testable hypotheses with the hope of collecting data to support the theory.

- Researchers need to name variables they will study and operationalize them

o When one operationalizes a variable, you explain how you will measure it.

o For example, w/ testing indep variable violent TV programs against dependent variable, people’s responses, when you operationalize the variables, need to consider what programs will be considered violent, what behaviors to be aggressive.

- Remember that a hypothesis cannot be proved, but can be supported/disproved.

Sampling

- Before investigating a hypothesis, one needs to decide what to study.

o The individuals which research will be conducted on are subjects or participants.

o The process by which subjects are selected is sampling.

§ In order to select a sample (group of subjects), one must first identify the population from which the sample will be selected.

o Population includes anyone that could be possibly selected in the sampe.

- Goal in selecting a sample is that it be representative of a large population.

o Better off with larger, more diverse population of 1000, and then randomly selecting a sample of 100.

o Random selection increases the likelihood that the sample represents the population.

- What is random?

o If one chose a sample by standing in front of the library and approaching people in a way I feel is random, I did not use random sampling.

§ Would have been less likely to approach people I did not know.

§ Also method mentioned would not represent schoo’s population.

· Not everybody walks past library on Wednesday morning.

o AR random sampling best done using a computer, table of random numbers, etc.

- Making a sample truly representative

o If I randomly select a sample of 100 people from population of 1000, sample will probably not reflect composition of school.

§ Example: If population has 500 males, 500 females, what are chances that the random sample will have the same 1:1 ratio?

· Not necessary to compute odds, however

§ Larger the sample, more likely it is to represent the population.

o So why not use all 1000 people?

§ Down side is time and money.

· Often for population psychologists, population is much larger than 10000.

§ AR large but not too large samples are optimum.

o If asked to design your own research on the AP exam, should specify the sample size and avoid using samples of extreme sizes, large or small.

- Can also increase representative trait of sample via stratified sampling

o Allows a researcher to ensure that the sample represents the population on some criteria.

§ If one thought that subjects of different racial groups might respond differently, I would want to make sure that I represented each race in the same proportion that it appears in the population.

Experimental Method

- Experiments can be divided into lab experiments and field experiments

o Laboratory experiments are conducted in a lab, a highly controlled environment.

§ Advantage is the control

o Field experiments are conducted out in the world.

§ Advantage is how it is more realistic.

- Students often equate research with experiments.

o HV know that many different kinds of research can be conducted, but only experiments can identify cause and effect relationships.

- Psychologists’ preferred method of research is the experiment because only through a carefully controlled experiment can one show a causal relationship

o Experiment 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, except for the independent variable that might affect the dependent variable.

o AR in order to show that violent TV programs cause the subjects’ aggression, I need to rule out any other possible cause.

§ An experiment can achieve this goal by randomly assigning subjects to conditions and by using various methods of control to eliminate differences (confounding variables)

- Assignment is the process by which subjects are put into a group, experimental or control.

o Random assignment means that each subject has an equal chance of being placed into any group

§ Benefit is that it limits the effect of subject-relevant confounding variables

· Example: if subjects given choice of choosing to watch violent TV or not violent TV, it is highly unlikely that two groups would be of similar people.

o Perhaps violent people prefer violent TV and would therefore select the experimental group.

§ Even if one assigned people to groups based on a seemingly random criterion, still some possibility of subject-relevant confounding variables

o TF using random assignments lowers chance that subjects in two different groups differ. In other words, it controls for subject-relevant variables.

o Random assignment controls for subject-relevant confounding variables.

- Note: When talking about differences between groups, will be talking about group average.

o A single very aggressive subject will not throw off results of entire group.

o Idea behind random assignment is that in general, the groups will be equivalent

- If one wanted to make sure experimental and control groups were equivalent on some criterion (ex. gender, IQ scores, age), one could use group matching.

o If one wanted a group for gender, would first divide sample into males and females, then randomly assign half of each group to each condition.

o Group matching will not result in the same number of males and females within each group.

§ Rather, half of males and half of females would be in each group.

- Situation-relevant confounding variables can also affect an experiment.

o For subjects to be equal isn’t enough.

o Situations into which the different groups are put must also be equivalent except for the differences produced by the independent variable.

§ Example: If experimental group watches violent TV in large lecture hall, and control group watches programs in a small classroom, their situations are not the same.

· AR any difference may be due to confounding variables and not the independent variable changes.

§ Other situation-relevant variables include time of day, weather, presence of other people in the room.

o Making environments of two groups as similar as possible controls for situation-relevant confounding variables.

- Experimenter bias is a special kind of situation-relevant confounding variable.

o Where experimenter bias is the unconscious tendency for researchers to treat members of experimental and control groups differently to increase the chance of confirming their hypothesis.

§ Note that experimenter bias is not a conscious act.

§ If researchers purposely distort their data, it is called fraud, not experimenter bias.

o Can be eliminated by use of a double-blind procedure.

§ This occurs when neither the subjects nor the researcher are able to affect the outcome of the research

§ Can be accomplished by having researcher have someone who does not know of the subjects’ condition to interact with the subjects.

· Single blind occurs when only the subjects do not know to which group they have been assigned.

§ This minimizes the effect of demand characteristics as well as certain kinds of response or subject bias.

o Demand characteristics are cues about the purpose of the study

§ Subjects use such cues to try to response appropriately.

o Response or subject bias is tendency for subjects to behave in a certain way

§ Example: Circle the midpoint on a scale or pick the right-hand option more than the left one.

§ One kind of response bias is called social desirability

· Is the tendency to try to give politically correct answers.

o Double blinds eliminate both experimenter and subject bias.

- Experiments typically involve at least one experimental group and a control group.

o Experimental group gets the treatment operationalized in the independent variable.

o Control group gets none of the independent variable.

§ Serves as a basis for comparison.

§ Without this, would not know whether changes in experimental group are due to experimental treatment or simply to any treatment at all is impossible.

· In fact, selecting a group for monitoring alone affects their performance (i.e. monitoring workers while they work would increase their performance) > this is known as the Hawthorne effect.

o TF continuing w/ TV example.

§ Experimental group might be shown “Die Hard” (a violent TV) while control group would view “When Harry Met Sally” (a comedy, or at least some other type of television)

§ Many experiments involve much more complicated designs.

· EX: additional groups could view other types of films and view differing amounts of violent content.

- One important method of control is the placebo method

o Whenever subjects in the experimental group are supposed to ingest a drug, participants in a control group are given an inert but otherwise identical substance.

§ Allows the researchers to separate the physiological effects from the psychological effects of people thinking they took a drug called the placebo effect.

- Sometimes using subjects as their own control group is possible, a procedure called counterbalancing.

o Example: if I wanted to see how frustration affected performance on an IQ test, I could have my subjects engage in a task unlikely to cause frustration, test their IQ, then give them a frustrating task and test their Iqs again.

o HV this procedure creates possibility of order effects

§ Subjects may do better on IQ test simply because they had the virtue from having taken the first IQ test.

§ This problem can be eliminated via counterbalancing

· Having half the subjects do the frustrating task first and half the subjects do the not-frustrating task first and then switching.

- Remember that a control group is not the only way of controlling an experiment.

Correlational Method

- A correlation expresses a relationship between two variables w/o showing cause.

o Can be positive or negative.

§ Where a positive correlation means that presence of one thing predicts the presence of another

§ Negative correlation has presence of one thing predicting the absence of another.

o Correlation is anything between –1 and +1

§ Where +1 = perfect positive correlation

§ -1 = perfect negative correlation.

§ Number 0 denotes weakest possible correlation – no correlation.

o Remember that correlation does not imply causation.

- Sometimes testing a hypothesis with an experiment is impossible.

o Example: Perhaps one wants to test hypothesis that boys are more likely to call out in class than girls.

§ Cannot randomly assign subjects to conditions.

· Boys are boys, girls are girls.

§ Assignment of the independent variable, in this case, has been predetermined.

§ TF can never be able to isolate the cause of the calling out behavior.

· Could be biological difference, or many of social influences that act on gender, etc.

o AR would have conducted an ex post facto study

- An even more popular research design is the survey method.

o Contrast with experimental method: Original hypothesis that “watching violent television programs makes people more aggressive” cannot be tested using the survey method because only an experiment can reveal a cause-effect relationship.

o However, survey method can be used to investigate whether there is a relationship b/w two variables, watching violence on TV and aggressive behavior.

§ In the survey method, neither of the variables are manipulated, TF there is no independent or dependent variable.

o In the survey method, the researcher can no longer control for subject-relevant confounding variables.

§ Some people can watch a lot of violent TV, others a few.

o Survey method does not enable the researcher to determine which of these differences cause a difference in violent behavior

- Flaws of the survey method

o Controlling for situation-relevant confounding variables using the survey method is possible (bringing all subjects in one place in one time to complete survey), but it is rarely done.

§ One of advantages of survey method is that survey is mailed and completed by their convenience

§ HV since people fill out surveys in different places, times, taking different amounts of times, research will be plagued by confounding variables.

o AR determining what causes difference in violent behavior close to impossible.

o A survey will also have few people send it back, and having a low response rate, will have people unlikely to make up a representative sample.

Naturalistic Observation

- Sometimes research opt to observe subjects in natural habitats without interacting with them at al

o Goal is of a naturalistic observation is to get a realistic and rich picture of the subjects’ behavior.

o HV control is sacrificed.

- Be sure to not confuse naturalistic observation with field experiments

o In a naturalistic observation, the researchers do not impact the behavior of the participants at all.

o In a field experiment, the researcher has manipulated the indep and dependent variable and attempted to eliminate as many confounding variables as possible.

Case Studies

- Final research method is the case study method

o Used to get a full, detailed picture of one subject or a small group of subject.

o Example: Clinical psychologists often use case studies to present information about a person suffering from a particular disorder

- Allows the researcher to get the richest possible picture of what they are studying

- Does not allow the researcher to generalize the findings to a larger population.

Statistics

Descriptive Statistics

- Descriptive statistics, as the name suggests, describes a set of data.

o Example: If interested in researching what kinds of pets schoolmates have, can summarize data by creating a frequency distribution that tells how many students have each.

o Where frequency distributions can easily turn into line graphs called frequency polygons or bar graphs known as histograms.

§ Where y-axis always represents frequency, and whatever you are grasphing (i.e. pets) is the x-axis.

- One group of statistical measures is measures of central tendency

o They attempt to mark center of a distribution.

o Three common types are median, mean, and mode.

§ Obvious/common knowledge to compute.

§ A distribution may have more than one mode, and would therefore be bimodal.

o Mean is most commonly used to measure central tendency, but its accuracy can be distorted by extreme scores or outliers

§ When a distribution includes outliers, the median is often a better measure of central tendency.

- Unless a distribution is symmetrical, it is skewed.

o Outliers skew distributions

§ Where if a distribution has an extreme score that is very high, distribution is said to be positively skewed.

§ If an extreme score is very low, it is negatively skewed.

o Where a positively skewed distribution contains more low scores than high scores, opposite for negatively skewed distribution.

o In positively skewed distribution, mean is higher than the median as outliers have a much more dramatic effect on the mean than the median.

- Another type of descriptive statistical measures is variability.

o Measures include range, variance, and standard deviation.

o Measures of variability attempt to depict the diversity of the distribution.

§ Range is range, standard deviation is the square root of variance.

· Both standard deviation and variance relate the average distance of any score in the distribution from the mean.

· Higher the variance and standard deviation, the more spread out the distribution.

- Comparing scores between different distributions.

o In order to do so, can convert scores from different distributions into measures called z scores.

§ Z scores measure the distance of a score from the mean in units of standard deviation.

§ Scores below the mean have negative z scores, opposite is true for positive z scores.

o Example¨If Clarence scored 72 on a test w/ mean of 80 and deviation of 8, his z score is –1.

- Often in psychology will see reference to a normal curve

o Normal curve is a theoretical bell-shaped curve for which the area under the curve lying between any two z scores has been predetermined.

§ Where approximately 68% of scores in a normal distribution fall within one standard deviation, and almost 95% fall within two standard deviations.

· Almost 99% of scores fall within 3 standard deviations.

o Normal curve is symmetrical and knowing that three numbers given above will allow you to calculate the approximate percentage of scores falling between any given z scores.

§ Example: 47.5% of scores fall between z scores of 0 and +2.

- While z scores measure the distance of a score away from the mean, percentiles indicate the distance from 0.

o Someone who scored in the 90th percentile scored better than 90% of the people who took the test.

o Clear relationship between z score and percentile

§ Scoring in the 50th percentile means having a z score of 0

§ Scoring in the 98th percentile means an approximate z score of +2.

Correlations

- A correlation measures the relationship between two variables

o Can be positive or negative

o Where strength of correlation expressed by a correlation coefficient.

§ Range from –1 to +1.

§ Both are equally strong correlation.

o Correlations may be graphed using a scatter plot.

§ The closer the points come to falling on a straight line, the stronger the correlation

§ Where the line of best fit is the line drawn through a scatter plot that minimizes the distance that minimizes the distance of all points from the line.

Inferential Statistics

- Where descriptive statistics provide a way to summarize information about a sample, the purpose of inferential statistics is to determine whether or not findings can be applied to a large population from which the sample was selected.

o Primary goals in selecting a sample is for it to represent its population.

§ Where guaranteeing that a sample is representative of a population is impossible

o TF the extent to which the sample differs from the population is sampling error.

§ Example: if testing whether sugar impacts memorization, and you have 2 groups of 10 people, gave them lollipop, one with sugar, one without, then asked them to recall 15 words, and the results were average: 7.0 and 6.9, it is right to be skeptical.

o Differences between groups are likely due to sampling error and chance.

§ Where purpose of inferential statistics is to help psychologists decide whether findings can be applied to larger population.

§ Inferential statistical tests include t-tests, ANOVAs, and MANOVAs.

· All take into account magnitude of difference and size of the sample.

o Most important to know all the tests yield a p value

§ Smaller the p value, the more significant the results.

§ P value of .05 is the cutoff for statistically significant results.

o Where p value of 0.05 means there is a 5 percent that results occurred by chance > as a result, scientists often try to replicate results to gather more evidence that findings not by chance.

§ P value can never be 0.

APA Ethical Guidelines

- Ethical considerations a major part of research design.

- Established by the APA (American Psychological Association) for human and animal research.

o Where any type of research must first propose the study to the ethics board or institutional review board (IRB).

§ Where the proposals are reviewed for ethical violations and/or procedural errors.

o Board gives researchers permission to go ahead to revise their plan.

Animal Research

- Strict requirements on how animals must be treated in laboratory experiments.

- Requires that experiments involving animals must have:

o Clear scientific purpose.

§ Animals are chosen because they are the best option.

o Must be cared for in a humane way.

o Must acquire all subjects legally.

§ Purchased from accredited companies.

§ Wild animals must not be trapped in an inhumane manner.

o Must design experimental procedures that employ least amount of suffering feasible.

Human Research

- Informed consent – Participants must know they are involved in research and give their consent.

o If participants are deceived in any way about the nature of study, deception must not be so extreme as to invalidate the informed consent.

- No coercion in that participation must be voluntary

- Participants’ privacy must be protected – must have anonymity/confidentiality.

o Identities/actions not revealed by the researcher.

o Participants have anonymity when researchers do not collect any data that enables them to match a person’s responses with name

§ In interview studies, researcher cannot promise anonymity but can guarantee confidentiality, meaning that researcher will not identify source of any data.

- Participants not be placed at significant mental or physical risk

o This clause requires interpretation by review board.

o Consideration highlighted by Stanley Milgram’s obedience studies in 1970s

§ Participants thought they were causing significant harm/death to others.

- Participants must be told purpose of study and provided with ways to contact researchers about study results ­– have sufficient debriefing procedures.

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