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

Correlation coefficient

Indicates directionof relationship

(positive or negative)

Indicates strengthof relationship(0.00 to 1.00)

r = +.37

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 variablesSaves $ and timeCan allow one to make predictionsAllows use of preexisting data

Disadvantages:Cant establish CAUSE & EFFECTProne to inaccurate reporting ( survey)Confounding variablesCant 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

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