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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