USU

a tool that we use to make objective decisions from subjective data

• represent data
• descriptive
• correlation
• inferential

• info collected on subject
• usually numbers - height, weight, scores
• sometimes words or categories

graphs or charts

• Measures central tendency
• Measures variability

• mean
• median
• mode

• range
• standard deviation

• aka average
• add points and divide by number of data points

• Order data points from least to greatest
• median is middle

most frequently occuring data point in series

difference between the least and greatest data point in series

tells how tightly all data points are clustered around mean in series of data. this is a measure of variability

• mean weight of students at 2 different schools
• graph the data

measure relationship between two varaibles cannot measure cause and effect

allow us to test hypothesis in an experiment for cause and effect while comparing

keeps bias out of experiement

used to determine if the means of two samples are significantly different

• level of significance of test
• he probability that two samples are likely to have come from the same two underlying populations that have the same mean