Statistics in AP Psychology

Learning Targets 1. Distinguish the purposes of descriptive statistics and inferential statistics. 2. Apply basic descriptive statistical concepts, including interpreting and constructing graphs and calculating simple descriptive statistics.

Descriptive Statistics Numbers that summarize a set of research data obtained from a sample. The purpose is to make data meaningful. Frequency Polygon Line Graph Histogram-Bar graph

Statistical Reasoning Misrepresentation may lead to incorrect conclusions.

Measures of Central Tendency Mean- the average Median- middle score Mode-most frequently occurring Range- Difference between the lowest & the highest number

Let’s Practice- On your notes 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. Consider cost of living? Find the mode, median & mean for the Dunder Mifflin Staff $25,000 - Pam $25,000 - Kevin $25,000 - Angela $100,000 - Andy $100,000 - Dwight $200,000 - Jim $300,000 - Michael

A Skewed Distribution: Outliers The mean doesn’t work below. The median is a much better measure.

Skewed Distributions Negative contains more high scores Positive skew contains more low scores

Standard Deviation Large SD= more spread out scores are from the mean How much scores vary across the mean (the average); Average distance of every score from the mean Large SD= more spread out scores are from the mean Small SD= more scores bunch together around the mean

Normal or Bell Curve

1. With a row partner study the 2 charts 2. Which class did better - the majority of the students did well? Which would you rather have if you were a teacher?

What does this mean?

Inferential Stats Infer as whole...apply to general population Can we make assumptions based off of our data? Are they significant enough to be applied to a whole high school? A whole nation? Infer as whole...apply to general population The purpose is to discover whether the finding can be applied to the larger population from which the sample was collected. If it worked for this sample, it will work for others.

Statistical Significance p = > 5% (or 0.05) In a study there we want results that are > 5% chance of fluke/error Your results are not random. This is really good for drug testing

Let’s Roll the Dice!