BASICS OF STATISTICS
Define statistics
What is the science of collecting, organizing, analyzing, and interpreting data?
Qualitative vs quantitative
Qual = categories, Quan = numbers
Simple random sample
Every individual has equal chance
Observational vs experiment
Observational = no treatment, Experiment = treatment imposed
Mean
Average
What is statistical thinking?
Thinking about data in context to make decisions
Discrete vs continuous
Discrete = countable, Continuous = measurable
Stratified sample
Divide into groups and sample from each
Explanatory vs response
Explanatory = causes change, Response = outcome
Median
Middle value
What is the statistics process?
Ask question → collect data → analyze → interpret
Example: qual or quan?
Answers vary (height = continuous, eye color = qualitative)
Cluster sample
Randomly select entire groups
Placebo
A fake treatment
Mode
Most frequent value
Parameter vs statistic
Parameter = population value, Statistic = sample value
Which graph for qualitative?
Bar graph
Sampling error vs bias
Sampling error is natural variation from using a sample; bias is systematic error
Double-blind
Neither subject nor experimenter knows who gets treatment
Standard deviation
Measures average distance from the mean
Population vs sample
Population = entire group, Sample = subset
Which graph for quantitative?
Histogram
Types of bias
Non-response bias, response bias, data entry errors
Matched pairs vs completely randomized
Matched pairs use related subjects; completely randomized assigns randomly
Resistant statistics
Median and IQR