Statistics and correlation
How might we use stats in psych?
Statistics
• How do we describe data?
-Gather raw data
-Frequency Distribution= number or
frequency of a behavior.
- X-axis=data you are graphing
- Y-axis= represents frequency
Histograms= Bar graphs
Measures of Central
tendency
• Mode- The score that occurs most
often
• Why Use?
• Median-the middle score
• How do we calculate median?
Calculator from Notebook
• Use calculator page here
Calculating Mean….
• Mean-The average of all scores
How do we calculate mean?
How can mean be distorted?
Outliers= example
Demo- Positive and negative skew
Measures of Variation
• The Wechsler IQ scale
• Range- gap between high and low
scores
• Standard deviation- measures the
degree to which scores deviate from
one another
• EX: IQ
Correlation
-Handout
 Correlation Coefficient
 A statistical measure that indicates how well either
factor predicts the other
Indicates direction
of relationship
(positive or negative)
Correlation
coefficient
r = +.37
Indicates strength
of relationship
(0.00 to 1.00)
Understanding
Correlations
• NOT Cause and effect
• Frosted Flakes prevents cancer,
oatmeal causes cancer ( Good
News Survey)
• TV watching is linked to childhood
obesity
Illusory Correlation
• The perception that a relationship
exists between two variables when
no relationship is present.
• Ex:
Correlation Research
• Advantages:
Can examine a relationship between two variables
Saves $ and time
Can allow one to make predictions
Allows use of preexisting data
Disadvantages:
Cant establish CAUSE & EFFECT
Prone to inaccurate reporting ( survey)
Confounding variables
Cant manipulate variables
Advantages/Disadvantages
of other Research Methods
• Experiments
• Case History
Advantages &
Disadvantages: Experiment
• Advantages:
• CAN establish cause and effect
• Can actively manipulate variables
via operationalization of variables
• Can use double blind procedure
• Can distinguish between real and
placebo effects
• Can be replicated
Disadvantages:
• Experiments may be artificial or
contrived
• Hard to establish controls, eliminate
confounding variables
• Probability of bias
• $ and time consuming
Others Methods of
Research:
• Case History= A biographical review of
patients relevant history.
• Advantages:
• - In depth info
- Rare Phenomena or unusual cases
- Preexisting cases don’t involve ethics
- Time and $ Factors
Case History:
- Disadvantages:
- Can’t generalize results
- Inaccurate reporting
- no cause and effect
Stop here
Naturalistic
Observation:
 Naturalistic Observation
 observing and recording behavior in
naturally occurring situations
• Advantages: natural setting
• Disadvantages: cant generalize,
variables are not controlled
Description
 Survey
 the self-reported attitudes or behaviors
of people
 representative, random sample of
people
Limitation:
Intentions are not always translated into
action
COMPUTER LAB
TOMMOROW
• Lab on correlation and stats
• Show website