--- title: "IQR | AP Stats Definition" description: "The Interquartile Range (IQR) is a measure of statistical dispersion that represents the range within which the central 50% of a dataset falls." canonical: "https://fiveable.me/ap-stats/key-terms/iqr" type: "key-term" subject: "AP Statistics" --- # IQR | AP Stats Definition ## Definition The Interquartile Range (IQR) is a measure of statistical dispersion that represents the range within which the central 50% of a dataset falls. ## What It Is The [Interquartile Range](/ap-stats/key-terms/interquartile-range "fv-autolink") (IQR) is a measure of statistical dispersion that represents the range within which the central 50% of a dataset falls. In [AP Statistics](/ap-stats "fv-autolink"), this term belongs to 1.7 [Summary Statistics for One Quantitative Variable](/ap-stats/unit-1/summary-statistics-for-quantitative-variable/study-guide/fDwLeu9W74iSnEcnKHOA "fv-autolink"). Use the notation and conditions attached to the procedure or model, then interpret the result in context. ## Why It Matters IQR supports [Unit 1](/ap-stats/unit-1 "fv-autolink"): Exploring One-Variable Data and Collecting Data. The relevant CED learning objectives cover calculate [measures of center](/ap-stats/key-terms/measures-of-center "fv-autolink") and position for quantitative data; calculate measures of variability for quantitative data. ## Connections ### 1.7 Summary Statistics for One Quantitative Variable IQR is used in this topic. Connect the definition to the topic's calculations and interpretations in context. ### [1.5×IQR rule (Unit 1)](/ap-stats/key-terms/1-5-iqr-rule) [1.5×IQR rule](/ap-stats/key-terms/1-5-iqr-rule "fv-autolink") appears with IQR in Topic 1.7. Use the two ideas together when a question moves from identifying the setup to interpreting the result. ### [Sensitivity to extreme values (Unit 1)](/ap-stats/key-terms/sensitivity-to-extreme-values) [Sensitivity to extreme values](/ap-stats/key-terms/sensitivity-to-extreme-values "fv-autolink") appears with IQR in Topic 1.7. Use the two ideas together when a question moves from identifying the setup to interpreting the result. ## On the AP Exam An AP question can ask you to identify the study design or describe data with the correct graph and summary. Name the concept precisely, show the relevant calculation when needed, and state the conclusion in the problem's context. ## Key Takeaways - The Interquartile Range (IQR) is a measure of statistical dispersion that represents the range within which the central 50% of a dataset falls. - IQR is mapped to 1.7 Summary Statistics for One Quantitative Variable in the current AP Statistics course. - On an AP question, use IQR as part of a complete calculation or interpretation, not as an isolated label. ## FAQs ### What is IQR in AP Statistics? The Interquartile Range (IQR) is a measure of statistical dispersion that represents the [range](/ap-stats/key-terms/range "fv-autolink") within which the central 50% of a dataset falls. ### Which AP Stats unit covers IQR? IQR appears in Unit 1: Exploring One-Variable Data and Collecting Data, especially 1.7 Summary Statistics for One Quantitative Variable. ### How does IQR appear on the AP exam? An AP question can ask you to identify the study design or describe data with the correct graph and summary. Name the concept precisely, show the relevant calculation when needed, and state the conclusion in the problem's context. ### Is IQR only a vocabulary term? No. Be ready to use it in a calculation, identify it in a setup, or interpret what it means in context. ## Structured Data ```json {"@context":"https://schema.org","@graph":[{"@type":"LearningResource","@id":"https://fiveable.me/ap-stats/key-terms/iqr#resource","name":"IQR | AP Stats Definition","url":"https://fiveable.me/ap-stats/key-terms/iqr","learningResourceType":"Concept explainer","educationalLevel":"AP® / High School","about":{"@id":"https://fiveable.me/ap-stats/key-terms/iqr#term"},"audience":{"@type":"EducationalAudience","educationalRole":"student"},"dateModified":"2026-08-04T00:38:30.677Z","isPartOf":{"@type":"Collection","name":"AP Statistics Key Terms","url":"https://fiveable.me/ap-stats/key-terms"},"publisher":{"@type":"Organization","name":"Fiveable","url":"https://fiveable.me"}},{"@type":"DefinedTerm","@id":"https://fiveable.me/ap-stats/key-terms/iqr#term","name":"IQR","description":"The Interquartile Range (IQR) is a measure of statistical dispersion that represents the range within which the central 50% of a dataset falls.","url":"https://fiveable.me/ap-stats/key-terms/iqr","inDefinedTermSet":{"@type":"DefinedTermSet","name":"AP Statistics Key Terms","url":"https://fiveable.me/ap-stats/key-terms"}},{"@type":"FAQPage","mainEntity":[{"@type":"Question","name":"What is IQR in AP Statistics?","acceptedAnswer":{"@type":"Answer","text":"The Interquartile Range (IQR) is a measure of statistical dispersion that represents the [range](/ap-stats/key-terms/range \"fv-autolink\") within which the central 50% of a dataset falls."}},{"@type":"Question","name":"Which AP Stats unit covers IQR?","acceptedAnswer":{"@type":"Answer","text":"IQR appears in Unit 1: Exploring One-Variable Data and Collecting Data, especially 1.7 Summary Statistics for One Quantitative Variable."}},{"@type":"Question","name":"How does IQR appear on the AP exam?","acceptedAnswer":{"@type":"Answer","text":"An AP question can ask you to identify the study design or describe data with the correct graph and summary. 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