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Glossary
Look up any term from this course. Each entry links back to the lesson that taught it.
| Term | Definition | Lesson |
|---|---|---|
| Complementary events | An event and "not" that event — their probabilities always add up to . | Complementary Events |
| Expected frequency | A prediction of how many times an event will occur: probability × number of trials. | Expected Frequency |
| Experimental probability | An estimate of probability from real data: (times the event happened) ÷ (total trials). Also called relative frequency. | Probability From Data |
| Frequency table | A table showing each value in a data set alongside how many times it occurs. | Frequency Tables |
| Independent events | Two events where one's outcome does not affect the other's probability — for these, P(A and B) = P(A) × P(B). | Combined Events: AND |
| Interquartile range (IQR) | The upper quartile (Q3) minus the lower quartile (Q1) — the spread of the middle half of the data. | Range and Quartiles |
| Mean | The sum of all values divided by how many values there are. | Mean, Median, and Mode |
| Median | The middle value of a data set once it has been ordered from smallest to largest. | Mean, Median, and Mode |
| Mode | The value that appears most often in a data set. | Mean, Median, and Mode |
| Mutually exclusive events | Two events that cannot both happen at the same time — for these, P(A or B) = P(A) + P(B). | Combined Events: OR |
| Probability | A number from (impossible) to (certain) measuring how likely an event is. | Introduction to Probability |
| Range | The highest value in a data set minus the lowest value. | Range and Quartiles |
| Sample space | The complete set of all possible outcomes of an experiment. | Introduction to Probability |
| Tree diagram | A diagram showing every possible outcome of a sequence of events, with probabilities multiplied along a path and added across matching paths. | Tree Diagrams |
| Types of data | Qualitative data is non-numeric; quantitative data is numeric, and splits into discrete (countable) and continuous (measured) data. | Types of Data |
More lessons in Descriptive Statistics and Basic Probability · Previous: Course Exam