AP Psychology

Research Methods

between-subjects designA between-subjects design is a study where subjects are either in one group or another, never both or parts of both.

For example, if a study was being done on which two types of painkillers worked best, subjects would be placed in one group or the other for best results.

case-study method

A case study is an intensive study of a single person, incident or community.

A famous case-study involved a mild-mannered railroad worker named Phineas Gage. In 1848, an explosion at work caused an iron rod to pierce through his Gage’s cheek and skull. His frontal lobe was severely damaged but he was alive and apparently unaffected. With the rod through his skull, he could talk normally to those around him. However, his personality changed, as he grew more argumentative, rude and according to this friends, immoral. His case was one of the first that suggested a neurological base for personality and behavior.

central tendency

The central tendency is a number that is used to describe the “average” score of distribution. This is done in one of three ways – mean, medium and mode.

confounding variablesConfounding of variables is when two variables are linked together in a way that makes it difficult to sort out their specific effects. It has happened often that a confounding of variables have ruined months or years of work and indeed, one of the measures of an experienced researcher is one’s ability to anticipate such things.

control group

The control group is the one which is treated the same way as the experimental group except that the independent variable is not applied.

If a scientist was doing a study on the impact of the presence of an iPhone during studying, the experimental group would be the one with the iPhone next to them as they performed a study assignment, given to the them by the scientist and the control group would be those without an iPhone.

correlation

A correlation refers to the measure of the relationship between two variables.

In the study of macroeconomics, there is something called Okun’s Law. It shows the relationship between the country’s unemployment rate and its potential gross domestic product (GDP). Okun’s Law states that for every 1% increase in unemployment, there is a 2% reduction in the country’s potential GDP. Okun’s Law was created to show a correlation between the two economic statistics or variables.

correlation coefficientCorrelation coefficient shows the direction and strength of the relationship between two sets of variables.

Positive correlations go in the same direction – the more money you make, the more expensive items you buy and vice versa. This is designated with a plus sign (+) before the coefficient. Negative correlations suggest an inverse relationship – the more one works, the less time they spend with the family and vice versa. This is designated with a minus sign (-) before the coefficient. If there is no sign before the coefficient, it is positive.

The strength of such a relationship is expressed between 0 and +1.00 if positive and 0 and -1.00 if negative. The nearer to 0, the greater evidence that no relationship exists. The nearer to either 1.00, the stronger the relationship.

counterbalancing

With experiments, scientists always try to account for every possibility or combination of possibilities. For psychologists, they do this with counterbalancing. If a scientist has multiple independent variables they want to present, they will make sure to present each variable to each group in their study to measure all possible outcomes. This can grow out of hand and problematic but some studies would allow for this approach more than others.

demand characteristics

There are many clever people out in the world and some they think they are clever. If a subject thinks they have an insight on the ultimate purpose of a study or what the researcher is looking for, some will try to modify their behavior to provide the “correct” response. They may not be correct (often, they are not) but simply the attempt to alter an otherwise honest response to the conditions of the study is referred to as a demand characteristic.

descriptive statisticsDescriptive statistics refers to the listing and summarizing of data in a practical, efficient way.

In geography, scientists use remote sensing in the form of satellites to collect data about the planet, from pollution to weather data. To do this, geographers require a computer called the Geographic Information System (GIS) that helps to condense and organize the data in a logical and digestible way – the results are descriptive statistics.

experiment and quasi-experimental

An experiment is a type of research method where the scientist manipulates variables and records results. With the results, the scientist can extrapolate meaning or significance.

With a quasi-experiment, the researcher manipulates variables but he does not randomly assign people to the groups within the experiment. The presence of these two qualities are usually signs of a true experiment.

experimental group

An experimental group is one to which an independent variable is applied.

If a scientist was doing a study of the impact of the presence of an iPhone during studying, the experimental group would be the one with the iPhone next to them as they performed a study assignment, given to the them by the scientists. The control group would be those without an iPhone.

experimenter bias (expectancy effect)

While psychologists, like any scientist, seeks the truth in an objective manner, expectations and beliefs can sometimes skew the conclusions drawn from a study. An experimenter bias is when a researcher’s expectations or references about the outcome of a study influence the results obtained.

In recent years, there has been a great deal of discussion on whether the climate change debate, suggesting that man is the cause of it, is not a product of the experimenter’s bias.

ex post facto studiesIn a true experiment, there is a random assignment of people into groups and the manipulation of independent variables to determine their impact on a dependent variable. An ex post facto study, from the Latin meaning “after the fact,” is a quasi-experiment where people are grouped by a preexisting condition – not random. Additionally, the independent variable impacted the subjects prior to the study.

So, an example of a ex post facto study would be studying people with glasses and trying to ascertain how much television they watched as children to determine if there is a connection.

frequency distribution

Frequency distribution is the organization of data so that trends can be scored or measured.

During war, armies have been able to crack secret codes by the frequency that certain letters, words or characters appear. It is a painstaking process but it has proven to be very successful.

frequency polygon

A frequency polygon is a line graph that shows statistical information and its distribution.

histogramA histogram is, in essence, a bar graph showing various aspects of statistic information. Unlike a bar graph, the bars touch one another to show no gap between the information shown in one bar and an adjacent one.

hypothesisA hypothesis is a measurable statement speaking to the relationships among the variables.

An example of an hypothesis could be:

The presence of vegetarianism in the developing world has more to do with a lack of wealth rather than a philosophical

stance.

interval scaleAn interval scale is a measure of showing the degree of variance between items or variables.

mean and medianTwo of three ways in which a set of data can be analyzed for its central tendency, mean (the arithmetic average of the scores in a distribution) and median (score that falls exactly in the center of the distribution of scores) are often used.

meta-analysisWhen there are inconsistent findings, researchers use meta-analysis, referring to combining the statistical results of many studies of the same question, yielding an estimate of the size and consistency of the variable’s effects. There are several method issues that can ruin or invalidate studies and are typically the target of such analysis.

mode, bimodal, multimodal

One of three ways in which a set of data can be analyzed for its central tendency, mode is the score that appears the most. As the name would suggest, bimodal refers to two oft appearing scores within the same statistical data. Additionally, more than two modes is referred to as multimodal.

naturalistic observationNaturalistic observation refers to a scientist studying subjects in their natural environment.

Jane Goodall, the British zoologist, has spent most of her adult life in Tanzania studying the world of chimpanzees. Her technique involves her living among them and after so long a time, she has become a part of the group.

nominal scale

A nominal scale is really not a scale at all in the way that most people think of it. It is a variation of the traits that are studied about a particular theme.

For example, if I was doing a study of high school students and the amount of time they spend on homework, the nominal scale might be made up of the different traits that I use to measure that statistic. With the students, I may be looking at them on the basis of gender, age, grades, etc. That would be my nominal scale.

normal distribution

A normal distribution refer to statistical data that is shown on a line graph as a normal curve – an equal number on either side of the central tendency. Indeed, either side of the central tendency is a mirror image of one another.

operational definitionPsychologist Steve Cole and a group of scientists theorized that people with repressed feelings, gay men in their study, would have a greater number of physical ailments – a physical manifestation of the struggles within. To be testable, the hypotheses and variables had to be clearly defined – the components which are operationally defined.

Operational definition describes the action or operations that will be used to measure or control a variable. In this case, one’s suppression of their sexual orientation was measured and regular check-ups were used to identify illness, particularly specific diseases such as cancer, pneumonia, bronchitis, sinusitis and tuberculosis.

ordinal scaleTypically seen in research tools like surveys or interviews, an ordinal scale is a means of categorizing responses that are ranked or in some type of order.

For example, you might take a survey that ask how much you like the psychology teacher and the options (ordinal scale) would include:

1. Best teacher I’ve ever seen2. Pretty good teacher3. He’s ok – I’ve seen better4. Easily one of the worse I’ve come across

The importance of the responses lie in the ranking of options.

percentile scoreA percentile score is meant to show how many scores fall at or below the score given. This is done to show how one response or result measures against all others that responded to the same assessment.

For example, IQ tests are often scored on a percentile score (among other types). So, if you took such a test and were told that you scored in the 77th percentile, that meant that 77% of respondents scored the same or worse than you did. In short, not bad.

placebo and placebo effect

The placebo effect refers to a change in the illness or behavior of a subject based on what they think is the effect of the “medicine” when nothing of substance has been given to them.

population and sample

A survey’s sample refers to a group of people that represents a larger population. It is a sub-group of the survey’s population and chosen carefully to represent the group as a whole.

random assignmentOne way to prevent extraneous or confounding of variables is the random way in which people are placed in one group or another. In a random assignment, all subjects have an equal chance of being assigned to any group or condition in the study.

random selection

An essential part of valid research, random selection is the true random choice of subjects for a particular research in hopes that in studying these subjects, one can truly study a microcosm of the society. The more random the selection of subjects is, the more control the researcher has over unintended variables impacting the findings.

range

A statistical range is a measure of how varied the data is. This is done by subtracting the lowest score from the highest score and adding one.

Therefore, if the final grades for this psychology class includes a 94 as the highest grade and 57 as the lowest grade, the range would be 38.

ratio scaleA ratio scale is one that allows for an absolute zero – where nothing measured exists. It allows for certain types of measurement such as something being twice as much or half as much. Such scales are used in the measurement of things such as income, years of work experience and GPA.

scattergrams or scatterplots

Scattergrams are a form of graph that shows a series of dots placed based on a x- and y-axis. The dots represent the relationship between the two variables highlighted in the graph. The purpose is to show the nature of the relationship between the two variables – be they positive, negative or if there is no relationship at all.

single-blind/double-blind procedures

In a single-blind experiment, one group does not know whether they have been subjected to the variable or not.

A scientist might give one group a pill that is supposed to enhance attention span and give the other group a placebo but the two groups are not sure which they are receiving.

In a double-blind experiment, neither the groups nor the researcher knows who has received and who has not received the variable.

standard score (z score)

In statistics, a standard score (also known as a z-score) highlights how an individual score relates to the mean score. Therefore, two assessments are being conducted here – one of the individual effort (which produces the individual score) and how it relates to the population.

What if you took two sections of psychology – a part one and two, for example. If you scored higher in the first class compared to the second class, it does not necessarily mean you did worse but you must compare to the mean score of each class.

statistical significance (p)

Statistical significance is when the probability that an observed finding is due to chance is very low (5 chances out of 100 or .05).

Significant does not mean important or interesting but simply does not fall into a matter of chance.

statisticsStatistics is a branch of mathematics involved with making conclusions and inferences from data.

subjects

Subjects (also known as “participants”) are persons or animals whose behavior is systematically observed in a study.

survey method

A survey is a research method in which people respond to questions. This survey can be oral or written.

testsreliability and validity

Tests, in the psychological vernacular, are assessments designed to list and/or measure individual traits within a particular point in time. In order for tests to be considered significant, the tests require a certain level of reliability (consistency) and validity (does what it was designed to do).

variable (dependent and independent)

A variable refers to any characteristic that is subject to change. Variables can be either quantitative or qualitative, independent or dependent.

variance and standard deviationA study’s variance refers to how much the scores in a data set vary from each other and from the mean. Standard deviation is an index of the amount of variability in a set of data. The standard deviation will be high or low based on the amount of variability. Typically, the variability can tell researchers whether the data supports their hypotheses.

within-subjects design

A within-subjects designed study exposes on particular group of subjects to all variables measured. The advantage is that it limits the results to the behavior of that single group only.

For example, you show a group of subjects a video of a blue Nissan racing around a track. You then show the subjects a video of a red Malibu racing around a track. You want to see if the group perceives any difference in speed (though both cars had equal time) based on the color of the car. By sticking to the one group and if that one group suggests the red car is going faster, you know the results are due to the perception of the group based only on the color.