STATS

• Population


  All items. Results are called parameters.
• Sample


  A portion of the population. Results are called statistics.
• Simple random sample


  Random sample taken without grouping.
• Systematic sample

  Every kth item is selected starting with a random first item.
• Stratified sample


  Data is grouped, and a random selection is taken from each group.
• Cluster sample


  Data is grouped, and random selection of groups is taken.
• Convenience sample

  No randomization, the most convenient group is used.
• Discrete Quantitative


  Values represent counts or measurements.
• Continuous Quantitative


  Values represent measurements.
• Categorical


  Values are not numbers, represent categories.
• Summary Tables


  Tables for one categorical variable.
• Contingency Tables

  Tables for two or more categorical variables.
• Pie Chart


  Graph for categorical variables.
• Bar Graph


  Graph for categorical variables.
• Pareto Chart


  Graph for categorical variables.
• Proportion


  Measurement studied for inference.
• Frequency Distributions

  Tables for one numerical variable.
• Dot plot


  Graph for quantitative variables.
• Stem and Leaf Plot


  Graph for quantitative variables.
• Histogram


  Graph for quantitative variables.
• Mean


  Average, balance point of the distribution.
• Mode


  Most frequent value, used for categorical variables.
• Median


  Middle number when data is ordered.
• Range


  Difference between maximum and minimum values.
• Standard Deviation


  Typical distance of observations from the mean.
• Quartiles


  Split data into four equal parts.
• Inter-Quartile Range

  Middle 50% of the data.
• Five Number Summary

  Minimum, First quartile, Median, Third quartile, Maximum.
• Boxplot


  Visual display of the five-number summary.
• Outliers


  Values that significantly differ from the rest of the data.
• Left Skewed


  Mean < Median, large values pulling mean higher.
• Right Skewed


  Mean > Median, small values pulling mean lower.
• Symmetric

  Mean = Median, no skewness.
• Empirical Rule

  Approximate percentages of data within standard deviations.
• Probability


  Chance of occurrence of an outcome.
• Law of Large Numbers


  Proportion of occurrences approaches a particular number.
• Sample Space


  List of all possible outcomes.
• Intersection

  Outcomes in both events.
• Union

  Outcomes in either event or both.
• Conditional probabilities


  Probability of event A given that event B has occurred.