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Psychological Research Methods Statistics

Excavating Human Behaviors

Psychology Research Methods

- A Scientific Attitude is critical
- Curiosity a passion to explore and understand.
- Skepticism psychologists, like other

scientists, approach the world of behavior with

curious doubt. The are constantly asking two

questions What does it mean? How do you know? - Humility an awareness and acceptance that we

may have to reject our own ideas or theories (if

they are proven wrong). - Critical Thinking a scientific approach

prepares/demands us to think smarter ? to

examine assumptions, evaluate evidence, and

assess conclusions.

Hindsight Bias

- The tendency to believe, after learning the

outcome, that you knew it all along. - With 20/20 hindsight, everything seems obvious.

After the Chris Brown / Rihanna incident.my

husband said he knew Chris Brown was a violent

kid!!! Did he really?

Overconfidence

- We tend to think we know more than we do.
- We tend to be more confident than correct!

82 of U.S. drivers consider themselves

to be in the top 30 of their group in terms of

safety 81 of new business owners felt they

had an excellent chance of their businesses

succeeding. When asked about the success of their

peers, the answer was only 39. (Now that's

overconfidence!!!)

Exercise Unscramble these Anagrams

- WREAT
- ETRYN
- GRABE

Anagram Solutions

- WREAT --- WATER
- ETRYN --- ENTRY
- GRABE --- BARGE

The Barnum Effect

Theres a sucker born every minute. P.T. Barnum

- It is the tendency for people to accept very

general or vague characterizations of themselves

and take them to be accurate. - Barnum Effect Experiment - Subjects take a bogus

personality test that produces a set of vague and

even self-contradictory statements such as "you

can be outgoing at times but at times you can

also be shy." When put in the correct context

people will say that this analysis captures them

to a "T."

Applied versus Basic Research

- Applied Research has clear, practical

applications. - YOU CAN USE IT!!!

- Basic Research explores questions that you may be

curious about, but not intended to be immediately

used.

Studying how kissing changes when you get older

is interestingbut thats about it.

Research on therapies for drug addicts has a

clear purpose.

Psychological Research Methods

- Psychology is an experimental science.
- Assumptions must be supported by evidence.
- Psychologists use a variety of research methods

to study behavior and mental processes. - Psychologists follow the same general procedure

when conducting research - Asking research questions
- Forming hypothesis (hypotheses)
- Testing the hypotheses
- Analyzing the data (results)
- And drawing conclusions
- Eventually, replicating research

The Scientific Method

- Step 1 Forming research questions
- Beginning with scientific curiosity and interest,

many research questions come from daily

experience, psychological theory, or common

knowledge. - Step 2 Forming hypotheses
- A hypothesis is a predicted answer the question

(or in other words, an educated guess).

The Scientific Method

- Step 3 Testing hypotheses
- Once a hypothesis has been formed, it must be

scientifically tested and proved right or wrong. - This part of conducting research is the actual

experiment. - Psychologists use a variety of methods to test

hypotheses. - Step 4 Analyzing Results
- Data is analyzed using statistics
- The more data collected,
- the more complex a task
- it is to analyze.

The Scientific Method

- Step 5 Drawing Conclusions
- Once the results have analyzed, a psychologists

can draw or make conclusions about his/her

questions and hypotheses. - Step 6 Replication
- Even when a research study carefully follows

proper procedures, its findings might just

represent a random occurrence. - To confirm the results and conclusions of a

research study, the study must be replicated. - The study must be repeated and it must produce

the same or similar results as before. - If there are different results, then the findings

of the first study are questioned.

Research Methods Terminology

Hypothesis

- Expresses a relationship between two variables.
- A variable is anything that can vary among

participants in a study. - Participating in class leads to better grades

than not participating.

Independent Variable

- Whatever is being manipulated in the experiment.
- Hopefully the independent variable brings about

change.

- If there is a drug in an experiment, the drug

is almost always the independent variable.

Dependent Variable

- Whatever is being measured in the experiment
- It is dependent on the independent variable.

- The dependent variable would be the effect of the

drug.

Operational Definitions

- Explain what you mean in your hypothesis.
- How will the variables be measured in real life

terms. - How you operationalize the variables will tell us

if the study is valid and reliable.

- Lets say your hypothesis is that chocolate

causes violent behavior. - What do you mean by chocolate?
- What do you mean by violent behavior?

Selecting Subjects

- Population all members of a given
- group (of study)
- Sample a subset of the population which is

representative of the whole population - Random Sample a sample in which every member of

the population has an equal chance of being

selected - Stratified Sample a sample in which each

subgroup of the population is represented

proportionally to its size in the population

Key Research Terminology

- Using a random sample that represents the whole

population, a researcher can generalize findings

to the entire population. - CAUTION Overgeneralization is the making of

generalizations using unrepresentative cases. It

is easy to do but typically erroneous. - False Consensus Effect the tendency to

overestimate the extent to which others share our

beliefs and behaviors

Methods of Collecting Data

- Survey commonly used in both descriptive and

correlational studies, questionnaire method

sampling many cases (individuals) in less depth - Case Study the study of one or more individuals

in great depth, to inform about an entire

population or sample - Testing psychological tests are given to
- measure certain mental processes, such as

intelligence, aptitude, or personality

The ideal case study is John and Kate. Really

interesting, but what does it tell us about

families in general?

The Survey Method

- Use Interview, mail, phone, internet etc
- The Good- cheap, anonymous, diverse population,

and easy to get random sampling (a sampling that

represents your population you want to study)

Survey Method The Bad

- Low Response Rate
- People Lie or just misinterpret themselves.
- Wording Effects

How accurate would a survey be about the

frequency of diarrhea?

Naturalistic Observation

- Observing and recording behaviors of an organism

in natural environment - No control- just an observer (do not manipulate

the environment) - This method does not explain behavior but

describes it

What are the benefits and detriments of

Naturalistic Observation?

Correlational Research

- Detects relationships between variables
- Does NOT say that one variable causes another

There is a positive correlation between ice cream

and murder rates. As more ice cream is eaten,

more people are murdered. Does that mean that

ice cream causes murder?

Types of Correlation

- Negative Correlation
- The variables go in opposite directions.

- Positive Correlation
- The variables go in the SAME direction.

Studying and grades hopefully has a positive

correlation.

Heroin use and grades probably has a negative

correlation.

Correlation vs. Cause Effect

- Correlation coefficient is a statistical measure

of relationship (it reveals how closely related

two factors are or how closely two factors vary

together and thus how well either one predicts

the other). - Positive and negative correlations are possible
- A relationship does not mean causation!!!
- For example, watching TV violence positively

correlates with aggressive behavior but does not

necessarily mean watching violence on TV causes

aggressive behavior.

Correlation Coefficient

- A number that measures the strength of a

relationship. - Range is from -1 to 1
- The relationship gets weaker the closer you get

to zero.

- Which is a stronger correlation?
- -.13 or .38
- -.72 or .59
- -.91 or .04

How to Read a Correlation Coefficient

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Experimental Method

Smoking causes health issues.

- Looking to prove causal relationships
- Cause Effect
- Laboratory v. Field Experiments

Eating too many bananas causes

Constipation

Experimental Research

- In an experiment, participants receive what is

called a treatment, such as a change in room

temperature or a new drug. - Then, psychologists carefully observe the

participants to determine how the treatment

influences their behavior.

Independent and Dependent Variables

- All research studies measure and observe

variables (factors), especially experimental

studies. - In an experiment, the independent variable is the

factor that the researcher manipulates (controls)

so that they can determine its effect on the

dependent variable. - The dependent variable is the factor that depends

on the manipulated independent variable(s).

Experimental and Control Groups

- The experimental group is a group of participants

who receive the treatment or manipulated

variable. - The control group is a group of participants who

do not receive the manipulated variable (instead

a placebo of sorts). - All other variables/factors are held constant (or

equal) for both groups (to try to isolate a cause

and effect relationship between independent

variable(s) of interest to the research

psychologist and the dependent variable. - If the research psychologist fails to manage the

other variables (or hold them constant), they

become confounding variables. Confounding

variables are baaaaad!!!

Beware ofConfounding Variables

- The object of an experiment is to prove that A

causes B. - A confounding variable is anything that could

cause change in B, that is not A.

- If I wanted to prove that smoking causes heart

issues, what are some confounding variables?

Lifestyle and family history may also effect the

heart.

Experimental Method continued

- Psychologists randomly place participants

(subjects) into one group or another. - EXAMPLE The effect of extracurricular activities

on students academic success. - Once subjects are randomly placed into the

control and experimental groups, the researcher

makes sure that all other variables are the same

for all students regardless of group. - Using this grouping method in the experimental

method is called a controlled experiment. - The Placebo Effect
- In research studies and in our daily lives, our
- expectations affect what happens to us.
- Feeling better simply because we expect to
- feel better and for no other reason is an
- example of the placebo effect.
- A placebo is a substance or treatment that
- has no effect apart from the persons belief

in it.

Experimental Method continued

- Single-blind vs. Double-blind Studies
- In a single-blind study, participants do not know

whether they are receiving the treatment (the

manipulated independent variable) or not. In

other words, they do not know if they are in the

experimental group or in the control group. - This process avoids the placebo effect.
- In a double-blind study, both participants and

researchers are unaware of who has placed in

which group.

Practice Identifying Independent Variable and

Dependent Variable

- In addition to finding the I.V and the D.V.,

identify - The experimental group/condition(s)
- The control group/condition
- A possible confounding variable
- Hint The third example has two
- experimental groups/conditions

Descriptive Statistics

- Just describes sets of data
- You might create a frequency distribution,

frequency polygons or histograms - Measures of Central Tendency
- (1) Mean The average of all scores in a

distribution - (2) Median The central score in a

distribution (middle) - (3) Mode The score that appears most

frequently in a distribution

Measure of Central Tendency

- Mean, Median and Mode.
- Watch out for extreme scores or outliers.

Lets look at the salaries of the employees at

Dunder Mifflen Paper in Scranton

25,000-Pam 25,000- Kevin 25,000-

Angela 100,000- Andy 100,000- Dwight 200,000-

Jim 300,000- Michael

The median salary looks good at 100,000. The

mean salary also looks good at about

110,000. But the mode salary is only

25,000. Maybe not the best place to work. Then

again living in Scranton is kind of cheap.

Normal Distribution

- In a normal distribution, the mean, median and

mode are all the same. - The mean is the most commonly used measure of

central tendency, but its accuracy can be

distorted by extreme scores or outliers.

Distributions

- Outliers skew distributions have a more

dramatic effect on the mean - If group has one high score, the curve has a

positive skew (contains more low scores) - Positively skewed the mean is higher than

the median - If a group has a low outlier, the curve has a

negative skew (contains more high scores) - Negatively skewed the mean is lower than

the median

Other measures of variability

- Range distance from highest to lowest scores.
- Standard Deviation the variance of scores around

the mean. - The higher the variance or SD, the more spread

out the distribution is. - Low SD indicates that the data points tend to

be very close to the mean - High SD indicates that data points are spread

out over a large range of values

Shaq and Kobe may both score 30 ppg (same

mean). But their SDs are very different!

Scores

- A unit that measures the distance of one score

from the mean. - A positive z score means a number above the mean.
- A negative z score means a number below the mean.

Normal Distribution

Decker Story

Approx. 68 of scores in a normal distribution

fall within 1 standard deviation point of the mean

Approx. 95 of scores fall within 2 standard

deviation points of the mean

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Inferential Statistics

- The purpose is to discover whether the finding

can be applied to the larger population from

which the sample was collected. - T-tests, ANOVA or MANOVA
- P-value .05 for statistical significance.
- 5 likely the results are due to chance.

Statistics Research Methods

- Null hypothesis (H0) is a hypothesis (scenario)

set up to be nullified, refuted, or rejected

('disproved' statistically) in order to support

an alternative hypothesis - Type I error the error of rejecting a null

hypothesis when it is actually true - Type II error the error of failing to reject a

null hypothesis when the alternative hypothesis

is the true state of nature

T-test

- The t-test assesses whether the means of two

groups are statistically different from each

other. This analysis is appropriate whenever you

want to compare the means of two groups - www.graphpad.com/quickcalcs/ttest1.cfm
- X mean of group
- Var Standard deviation of group
- N number in sample

Research Statistics Assignment 1

- Gather shoe size data from 10 females and 10

males, recording the shoe size of each. - Then calculate the measures of central tendency

(mean, mode, median) and graph the data set in a

frequency histogram or box-plot for both the

female findings and the male findings. - Find and discuss any outliers
- Explain the gender difference, if one exists.

Research Statistics Assignment 2

- Using the Research Question How many pairs of

shoes do males and females own? Write a testable

hypothesis. - Next, gather data from 10 females and 10 males,

recording the number of shoes owned by each. - Ask your participants, How many pairs of shoes

do you own? and (obviously) record their answer

and gender. - Calculate the measures of central tendency and

standard deviation and test for differences

between means using a t-test. (use

www.graphpad.com/quickcalcs/ttest1.cfm to help

you calculate a t-score) - Write a brief conclusion about your results (at

least 1 paragraph). Make sure you give an

explanation for the differences between the

gender.

Mr. Q is Definitely an Outlier!

APA Ethical Guidelines for Research

- IRB- Internal Review Board
- Both for humans and animals

Animal Research

- Clear purpose
- Treated in a humane way
- Acquire animals legally
- Least amount of suffering possible

Human Research

- No Coercion- must be voluntary
- Informed consent
- Anonymity
- No significant risk
- Must debrief