Intro to Research: How Psychologists Ask and Answer Questions

Correlation and Description

What you need to know by the end of the day….

• Differentiate types of research with regard to purpose, strengths, and weaknesses.– Why use each type of research method

• Describe how research design drives the reasonable conclusions that can be drawn.– How can each research method best be used

based on their results

Correlation

POSITIVE CORRELATION• Two variables increase

together or decrease together

• Example: The number of gallons of

gas pumped is positively correlated to the amount spent on gas.

NEGATIVE CORRELATION• Variables move in opposite

directions

• Example: Miles traveled is

negatively correlated to the amount of gas left in your tank.

The measure of the relationship between two items or variables

No relationship (0.00)Perfect negative

correlation (-1.00)

Scatterplots

Perfect positivecorrelation (+1.00)

Scatterplot is a graph comprised of points generated by values of two variables. The slope of points depicts the direction, and

the amount of scatter the strength of relationship.

Correlation Coefficient

Correlation coefficient

Indicates directionof relationship

(positive or negative)

Indicates strengthof relationship(0.00 to 1.00)

r = 0.37+

Statistical measure that shows the degree of relationship between two

variables

Number will always fall between -1.0 and +1.0

The higher the number the stronger the relationship

Correlation Coefficient Examples

• - 0.78moderately strong negative

• + 0.05very weak positive

• - 0.43moderately weak negative

• + 0.92very strong positive

What kind of relationships do the following correlations have?

Another example….Scatterplot showing relationship between height

and temperament in people. What kind of relationship is depicted?

Moderately positive… +.63

or

Correlation and Causation

Knowing that two items are correlated does NOT necessarily tell us why or exactly how they are related!!

CORRELATIONCAUSATION

3 types of Research

1. Descriptive (Observational)- simply describing a behavior

2. Correlation- finding the relationship between two variables

3. Experiment- controlled setting, manipulated variables

Naturalistic ObservationObservation of human or animal behavior in the environment in which it typically occurs

Jane Goodall’s study of chimpanzee culture

Naturalistic Observation• Valuable where other methods are

likely to be disruptive or misleading• Problems with Naturalistic

Observation– If people know they are being observed,

they tend to act differently than they normally would

• Ethically you usually must tell people you are observing them, yet can combat by observing for a long period of time

– Observations can be distorted if observers expect to see certain behaviors

• Why would this be a problem? How could it be solved?

Case StudyIntensive examination of the behavior and

mental processes associated with a specific person or situation

http://behavioralhealth.typepad.com

Case study• Are useful when something is new,

complex or fairly rare– Often used in clinical work and

neuropsychology

• Limitations…– May contain evidence that a certain research

thought to be important (why would this be a problem?)

– Are unlikely to be representative of people in general

• Yet…provide valuable material for further research and serve as testing ground for new treatment, training programs & other applications of research

SurveyA technique for ascertaining the self-

reported attitudes, opinions or behaviors of people usually by questioning a

representative, random sample of people.

http://ww

w.lynnefeatherstone.org

Surveys

• Validity of data depends upon:– How questions are worded– Representativeness of people surveyed

(why?)

• Other limitations…– Willingness of people to honestly

complete the survey– People may say what they believe they

should say about an issue

• Still a great way to gather LARGE amounts of information

Quasi-experiments

Studies that have the same “control” as experiments yet do not include the random

assignment of participants

EXAMPLEResearchers want to test hypothesis

that a pregnant woman’s use of drugs will cause abnormalities in her

developing baby.

Could you ethically randomly assign women who are 8 weeks pregnant to a group that will be snorting cocaine 3 times a day? Why or why not?

Quasi-experiments

Conclusions are not as firm as those drawn from true experiments, yet they allow

research to be conducted on topics and in settings that would otherwise be

impossible