Applied Research Studies Conducted to Solve Practical Problems

Research Methods

Terminology

applied research—studies conducted to solve practical problems

basic research—studies of interest to psychology but not applicable to solving immediate, real-world issues

replication—sufficient detail in the procedure section to duplicate the experiment with the same materials and instructions

Variables

independent variable—what the experiment manipulates; commonly the experimental and control groups

dependent variable—what is being measured; should be measurable with numbers

confounding variables—variables that are unintended and throw off the experimental results

counterbalancing—an attempt to spread out any ill effects of confounding variables

operational definition of variables—when an independent variable is defined according to the events used to produce it (e.g. what constitutes “low anxiety” or “high anxiety”); a measured operational definition applies to dependent variables that are defined in operational terms

research (or experimental) hypothesis—a detailed explanation of a predicted relationship between certain conditions or variables; this hypothesis is not subject to change

null hypothesis—a detailed statement indicating there is no relationship between certain conditions or variables

Validity and Reliability

reliability—the ability to produce consistent and stable scores or results

validity—the ability of a measuring instrument or experiment to measure what is intended

internalvalidity—controls prior influence, maturation processes and the order effect, but not the subjects’ history with the task

externalvalidity—controls the subjects’ history with the task but not the other aspects

Quantitative Research Methods

these methods are used by psychologists to test hypotheses under rigorous, controlled conditions

experiments take place in the laboratory or in the field

the aim is to establish a cause-and-effect relationship through descriptive and inferential statistics

statistics allow the researcher to determine the level of significance (at least at the .05 level)

Samples

population—the total number of people or things from which to draw a sample

sample—a small group of people or things selected to represent the target population

randomsampling—selecting a sample from the population purely at random

representativesampling—occurs when the population is divided into subpopulations and then a random sample is taken from each subpopulation

stratifiedsampling—a sample that matches the overall characteristics of the population from which it is drawn

systematicsampling—a sample that is pulled from the population using a system or some criteria, such as every 10th person

convenience sampling—participants are chosen based on availability (existing classes, individuals walking into a store, participants at a self-help group)

independentsubjects(between-subjects) design—a design in which groups of subjects experience different experimental conditions; comparing a control group versus an experimental group is a common independent samples design; measures two distinct groups

matchedpairsdesign—a design where subjects are matched on one variable, and then one subject is given one condition of the independent variable and the other subject is given the other condition (usually experimental and control conditions)

repeatedmeasuresdesign (within-subjects design)—a design in which one group is measured before and then after administration of a variable; typically this involves a pretest and a posttest

singleparticipant/subjectdesign—a design in which one subject’s performance over time or across experimental conditions is tracked and recorded; this is not the same as a case study

Participant Controls

history—subjects have existing experience or skill involving the issue tested (e.g. a student has attended study skills classes to help with memorization and the issue being examined involves memorizing a list of terms)

selection bias—there is a systematic error in your sample (e.g. there is a disproportionate amount of males versus females in your sample)

mortality—refers to subjects dropping out of the experiment part way through

maturation—refers to a change in the subject after the study begins (this is more likely if the experiment is run over several days)

diffusion of treatment error—this occurs when subjects share information with one another outside the study (e.g. students completing a math activity share their answer with subjects not yet being tested)

order effects—an error in the order of experimental tasks (counterbalancing fixes this)

constancy of condition—a change in the room or conditions in the experiment (it’s always best to run the study in the same location at the same time)

Ethical Considerations

there are five basic ethical considerations you need to address in any sort of research study:

informed consent--subjects should be told briefly what will be involved in the psychological experiment.
justification for any discomfort or deception--you need to justify why you would cause a subject any physical or mental discomfort, or deceive them in some way
right of withdrawal--at all times, subjects have a right to withdraw from the experiment
findings are confidential--while you can ask demographic information such as age, grade level, sex, or GPA, you cannot record their names in connection with their results
participants are debriefed--all subjects should be debriefed at the conclusion of your experiment

Experimental Method

experimentalgroup—a group that receives the experimental condition; the group that is affected by the independent variable

controlgroup—a group that does not receive the experimental condition; the group is not affected by the independent variable

placebogroup—a group that is a control group but receives a placebo to minimize subject bias (a single blind experiment)

single-blind techniques—an experimental design in which subjects do not know which group they are in, typically an experimental or control group; this reduces subject bias

double-blind techniques—an experimental design in which both the subjects and the experimenter do not know which group is which; this reduces both subject and experimenter bias

research bias and expectancy (researcher and participanteffects)—bias that occurs

demand characteristics—a cuing in process which insidiously instructs subjects in an experiment about what is expected (e.g. compassionate behavior, aggressive behavior, etc); if deception is used as to the purpose of the experiment, such subject bias arising out of demand should not occur

participant and researcherexpectancies—based on the idea that what the researcher expects will alter the subject’s performance; this is known as the Pygmalion effect; this was shown by Rosenthal’s study that experimenter expectancies can alter the performance of children in a classroom (our 40 Studies article “What You Expect Is What You Get”; this highlights the need to control experimenter bias

Surveys

large-scale and small-scale surveys—the scale of the survey is dependent on the number of surveys collected, either a lot (large scale) or a few from a select group (small scale)

ex post facto studies take an effect and look back to determine the likely cause

use of Likertscale—a rating scale developed by R. Likert where respondents are asked to indicate where they fall along some dimension; this is then converted into a numerical score (e.g. strongly agree-1, agree-2, neither agree nor disagree-3, disagree-4, strongly disagree-5)

advantages include:

flexibility in asking questions
less time to collect data
large amounts of data can be collected at once

disadvantages include:

question-bias
self-report bias
erroneous memories of the subjects
social desirability bias

Naturalistic Observation

participantobservation—the observer is part of the group being observed

non-participantobservation—the observer remains detached from the group; sometimes called a complete observer

methods of recording data, including time, event and point sampling:

durationrecording—the observer specifies the length of time a particular behavior will last (e.g. talking to other student; being out of one’s set)

frequency-countymethod—counting the number of time (frequency) the behavior occurs

intervalrecording—a single subject is observed for a set amount of time and the subject’s behavior is recorded

advantages of observations include:

lessening self-report bias and social desirability
information is not limited to what the subject can recall

disadvantages include:

difficulty in measuring complex behavior
expense

Descriptive Statistics

levels of measurement

nominal scale—a unit of measurement using named categories such as eye color, gender, voting status, etc.; no order and no indication of how groups differ are apparent; this is the least refined of the four measurement scales; used frequently in non-participant observations
ordinal scale—a unit of measurement in which values to a variable can be rank ordered from highest to lowest, such as class rank, percentile ranks, ordering ideas from best to worst, etc.
interval scale—a unit of measurement similar to ordinal scales but in which the difference between each unit is equal or constant; the difference between 5 and 6 is the same as between 17 and 18
ratio scale—a unit of measurement based on ordinal and interval scales but comparisons can be made using ratios; saying a number to two or three times greater than another number; this is the most refined of the four measurement scales; used frequently in lab and field experiments

measures of central tendency

mean—the average score from a group of scores

mode—the most frequent scores that occurs in a group of scores

median—the middle scores in a group of scores that separates the top half from the bottom half from rank-ordered scores

measures of dispersion

range—the difference between the highest and lowest score
standard deviation—a numerical index that tells, on average, how far the scores fall from the mean; the larger the standard deviation, the greater the spread of scores
variance—the second moment around the mean; the expected value of the square of the deviations of a random variable from its mean value
quartile and semi-interquartile range—divides ranked data into four parts or quartiles

Inferential Statistics

probability—an estimation of how many times a certain event is likely to happen

levels of confidence—the level of certainty that an inferential statistic is not due to chance

in experimental research .05 is the accepted minimum level of confidence
in other words, there is less than a 5% chance that are results are in error

non-parametric tests—tests in which the results do not fall into a normal distribution

chi-square test—a statistical procedure for use with nominal (frequency counts) and ordinal; usually used in naturalistic observations
Mann-Whitney U test—a test for use with two independent samples; the basis of this test is that if all the data from the two samples are ranked, the high and low ranks should be evenly distributed if the samples are equal; usually used in field or lab experiments

Graphical Techniques

bar chart—a graph using bars to denote numerical counts