Let’s Summarize

• The main purpose of statistics is to analyze data to draw conclusions about a larger population in order to answer a research question.
• Descriptive statistics involves numerical summaries and graphs of data. The type of numerical summary (means versus proportions) and type of graph depends on whether the data was quantitative or categorical.
• Inferential statistics can only be done when data is gathered from a sample that is representative of the population or data comes from a well-designed experiment.
• Various random sampling methods help ensure the sample is representative of the population.
• A well-designed experiment uses random assignment to assign participants to treatments, which creates similar treatment groups. With random assignment, we can be fairly confident that any differences we observe in the response of treatment groups is due to the explanatory variable.