Chapter 2 methods and statistics

• Psychodynamic• Behavioral• Humanistic• Cognitive• Biological• Sociocultural

• Do genes effect your personality?

• Can study habits be learned?• How do people from different

cultures interact?• How do negative childhood

experiences affect how people view stressful situations?

• How can I achieve my goal of becoming a doctor?

• What effect will rewards have in training my dog?

Hindsight Bias is the “I-knew-it-all-along” phenomenon.

After learning the outcome of an event, many people believe they could have

predicted that very outcome. We only knew the dot.com stocks would plummet after

they actually did plummet.

Hindsight Bias

OverconfidenceSometimes we think we know more than we actually know.

Anagram

BARGEGRABE

ENTRYETYRN

WATERWREATHow long do you think it

would take to unscramble these

anagrams?People said it would

take about 10 seconds, yet on average they took

about 3 minutes (Goranson, 1978).

Critical Thinking

Critical thinking does not accept arguments and

conclusions blindly.

It examines assumptions,

discerns hidden values, evaluates

evidence and assesses

conclusions.The Amazing Randi

Courtesy of the Jam

es Randi E

ducation Foundation

Scientific Method

Psychologists, like all scientists, use the scientific method to construct

theories that organize, summarize and simplify observations.

A Hypothesis is a testable prediction, that describes the relationship

between two variables.

They are often prompted by a theory, to enable us to accept, reject or revise

the theory.

Hypothesis

• Observe in a natural setting without interfering• Example: Rosenhan’s Mental Hospital Study

(1973)– Pseudopatients checked themselves into

mental institutions and faked schizophrenia – Demonstrated that normal people cannot be

distinguished from the mentally ill– “If they are here, they must be crazy”– People who are treated in a certain way over

time may begin to behave that way

• Involve an intensive investigation of one or more participants

– Results cannot prove or disprove anything, but can be used to generate new hypotheses

– Used by Freud• Anna O.

• Information is obtained by asking many individuals a fixed set of questions

– Can include both interviews and questionnaires• Interviews allow for modification

• Questionnaires take less time and reduce the possibility the researcher will influence the participant

How Surveys are conducted

• Establish your population.

• Population: all people with the characteristics a researcher wants to study.

• Example: all high school seniors in the U.S., all retired teachers in Rhode Island

How Surveys are Conducted cont.

• Most populations are too large to study. Therefore, samples are drawn from the populations.

• Sample: a limited number of cases drawn from the larger population.

How Surveys are Conducted cont.

• representative sample: sample that accurately reflects the characteristics of the population

• The most common way to gather a representative sample is by random, or chance.

• Studying the same group of people at regular intervals over a period of years to assess how certain characteristics change or remain the same during development– Minnesota Twin Family Study

• Twins reared apart study- twin similarities are a result of genes

• Able to estimate the heritability of

traits

Cross-Sectional Study

• A research technique that compares individuals from different age groups at one time

• Study a number of subjects from different age groups and then compare the results

• Cheaper, easier than longitudinal studies, but group differences may be due to factors other than development.

Longitudinal/Cross Sectional Study

Correlation

• This is the measure of a relationship between two variables or sets of data.

• When one trait or behavior accompanies another, we say the two correlate.

• CORRELATION DOES NOT EQUAL CAUSATION!

• Can be positive or negative• Example: vaccines and autism

– The majority of autistic children are diagnosed between the ages of 18 months and 3 years old.

– Children receive many immunizations in this same period of time.

Correlation

When one trait or behavior accompanies another, we say the two

correlate.

Correlation coefficient

Indicates directionof relationship

(positive or negative)

Indicates strengthof relationship(0.00 to 1.00)

r = 0.37+

Correlation Coefficient is a statistical measure of the relationship between two

variables.

Perfect positivecorrelation (+1.00)

Scatterplot is a graph comprised of points that are generated by values of two

variables. The slope of the points depicts the direction, while the amount of scatter depicts the strength of the relationship.

Scatterplots

No relationship (0.00)Perfect negativecorrelation (-1.00)

The Scatterplot on the left shows a negative correlation, while the one on the right shows no

relationship between the two variables.

Scatterplots

Correlations

•Range from -1.00 to +1.00–The greater distance from 0, the stronger the correlation

•Positive correlations indicate that as one variable increases, the other increases

too

•Negative correlations indicate that as one variable increases, the other

decreases

• One young woman died in fear in a most peculiar way: When she was born on Friday the 13th, the midwife who delivered her and two other babies announced that all three were hexed and would die before their 23rd birthday. The other two did die young. As the third woman approached her 23rd birthday, she checked into a hospitals and informed the staff of her fears. The staff noted that she dealt with her anxiety by extreme hyperventilation (deep breathing). Shortly after her birthday, she hyperventilated to death.

• A situation in which a researcher’s expectations influence that person’s own behavior, and thereby influence the participant’s behavior– We consciously or unconsciously tip off

people to what are expectations are; people pick up on those cues and act as expected.

Variables

• Variables are factors that are capable of change.

An Independent Variable is a factor manipulated by the

experimenter. The effect of the independent variable is the focus of

the study.

Independent Variable

A Dependent Variable is a factor that may change in

response to an independent variable. In psychology, it is usually

a behavior or a mental process.

Dependent Variable

Experimental Group

• The participants in an experiment who are exposed to the independent variable

• Also called the experimental condition

• The group being studied and compared to the control group

Control Group

• The participants in an experiment who are not exposed to the independent variable

• Results are compared to those of the experimental group

• Also called the control condition

• Enables the investigator to control the situation and decrease the possibility that outside variables will influence the results– Hypothesis– Variables (Independent and Dependent)-

If/then– Experimental Group and Control Group– Results must be replicated

• Methods of conduct or standards for proper behavior– Informed consent– Protection from harm– Confidentiality– Debriefing

• Single-Blind Experiment- participants are unaware of which participants received the treatment

• Double-Blind Experiment- neither the experimenter nor the participants know which patient received which treatment– Drug evaluation studies

• 1960- Would participants administer painful shocks to others merely because an authority figure had instructed them to do so?– 2000 male participants– Told they were participating in a study on learning– Each time the learner made a mistake, the

“teacher” was ordered to push a button to deliver an electric shock

– Shocks were false, but they did not realize this because the learners displayed distress and pain

• 65% of the volunteers pushed the shock button until they reached maximum severity

• Implied that ordinary individuals could easily inflict pain on others if such issues were ordered by an authority figure.

• Ethical issues?

• Replication?– Has been replicated with young, liberal college

students

http://www.youtube.com/watch?v=0PassGyF8X8&feature=related

• A change in the participant’s illness or behavior that results from a belief that the treatment will have an effect, rather than the actual treatment

•

• What type of correlation did we find between height and shoe size?

• What would a graph of a negative correlation look like? No correlation?

• What intervening variables might have been at work affecting our results?

• The branch of mathematics concerned with summarizing and making meaningful inferences from collections of data

• The listing and summarizing of data in a practical and efficient way, such as through graphs and averages

Hours Spent StudyingHours Spent Studying FrequencyFrequency

00 22

.5.5 88

11 1515

1.51.5 1010

22 66

2.52.5 33

33 11

TotalTotal 4545

• Mean

• Median

• Mode

• A measure of the difference or spread of a set of data

• Range – Subtract the lowest from the highest

• Standard Deviation– Average distance of every score from the mean– The larger the standard deviation, the more

spread out the scores are

• Describes the direction and strength of the relationship between two variables

• Pearson Correlation Coefficient = r– (+)= positive- as one variable increases, so

does the second variable– (-)= negative- as one variable increases, the

second variable decreases– Can range from -1 to 1 including 0

• Roll your die 10 times. Make note of the results.• Make a frequency distribution• Make a frequency polygon• Find the mean, median, and mode of the data

– Mean= sum of all rolls/10– Median- what was the median number of

times rolled?– Mode- what number was rolled the most

frequently?