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How do you report interquartile range?
Interquartile range is a range, so a difference between third and first quartiles IQR = Q3 – Q1. So it is a single number statistic, so this is exactly how you report it.
What is the importance of quartiles?
Quartiles tell us about the spread of a data set by breaking the data set into quarters, just like the median breaks it in half. For example, consider the marks of the 100 students below, which have been ordered from the lowest to the highest scores, and the quartiles highlighted in red.
What is the meaning of the interquartile range?
Interquartile range The interquartile range is a measure of spread used most commonly with the median. It represents the central portion of the distribution, from the 25 th percentile to the 75 th percentile. In other words, the interquartile range includes the second and third quartiles of a distribution.
When to report the median with the interquartile range?
When you have a skewed distribution, I find that reporting the median with the interquartile range is a particularly good combination. The interquartile range is equivalent to the region between the 75th and 25th percentile (75 – 25 = 50% of the data). You can also use other percentiles to determine the spread of different proportions.
Which is better the standard deviation or the interquartile range?
Additionally, the interquartile range is excellent for skewed distributions, just like the median. As you’ll learn, when you have a normal distribution, the standard deviation tells you the percentage of observations that fall specific distances from the mean. However, this doesn’t work for skewed distributions, and the IQR is a great alternative.
Are there any outliers in the interquartile range?
Outliers are values below Q 1 -1.5 (Q 3 -Q 1) or above Q 3 +1.5 (Q 3 -Q 1) or equivalently, values below Q 1 -1.5 IQR or above Q 3 +1.5 IQR. These are referred to as Tukey fences. 6 For the diastolic blood pressures, the lower limit is 64 – 1.5 (77-64) = 44.5 and the upper limit is 77 + 1.5 (77-64) = 96.5.