Quartiles & IQR - v2

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What is a quartile?

Back

A quartile is a type of quantile that divides a ranked dataset into four equal parts, each containing 25% of the data.

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How do you find the median of a dataset?

Back

To find the median, first sort the data in ascending order. If the number of observations is odd, the median is the middle number. If even, it is the average of the two middle numbers.

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What is the upper quartile (Q3)?

Back

The upper quartile (Q3) is the median of the upper half of a dataset, representing the 75th percentile.

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What is the lower quartile (Q1)?

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The lower quartile (Q1) is the median of the lower half of a dataset, representing the 25th percentile.

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What is the Interquartile Range (IQR)?

Back

The Interquartile Range (IQR) is the difference between the upper quartile (Q3) and the lower quartile (Q1), calculated as IQR = Q3 - Q1.

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How do you calculate Q1 in a dataset?

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To calculate Q1, first find the median of the lower half of the dataset (excluding the overall median if the number of data points is odd).

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How do you calculate Q3 in a dataset?

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To calculate Q3, first find the median of the upper half of the dataset (excluding the overall median if the number of data points is odd).

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What does it mean if the IQR is large?

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A large IQR indicates a wide spread of the middle 50% of the data, suggesting greater variability.

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What does it mean if the IQR is small?

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A small IQR indicates that the middle 50% of the data points are close together, suggesting less variability.

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What is the significance of quartiles in data analysis?

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Quartiles help to understand the distribution of data, identify outliers, and summarize the data set.