Is an interquartile range different to a normal range?

Hi, both can be used to find out the spread of values in a dataset. A normal range refers to a spread of numbers where the smallest number can be subtracted from the biggest number to find the middle half of the range. In comparison, an interquartile range refers to calculating the middle half of the range using the 25% and 75% percentiles in the dataset. The main difference in these methods is the fact that the interquartile range is not affected by outliers whereas the normal range is.

Hey! The standard range relates to the difference between the largest and smallest numbers that can then be used to find the mid point. However, the interquartile range refers to the difference between the 25% and 75% percentiles. This reduces the extreme data.

Yes. The range of a dataset is the biggest number minus the smallest number. The interquartile range (think inner quarter so 25%, 75%) is the 75th percentile minus the 25th percentile. Try calculating it with a few different data sets and you should see why this might be used instead of the full range. Which is most useful will depend on the type of data being looked at.

Range is the difference between the largest and smallest values in a data set (e.g. consider the numbers 1, 2, 3, 4, 5 - range = 5 - 1 = 4)

Interquartile range is the difference between the largest and smallest quartiles of a data set, i.e. IQR = Q3 - Q1

The interquartile range is the difference in value between the upper quartile and lower quartile. The upper quartile is the median of the upper half of a data set. the lower quartile is the median of the lower half of the data.

Yes, the normal range is the difference from the highest to the lowest value.

The interquartile range is the difference from the upper quartile (75%) to the lower quartile (25%)

The range of a set of data is the difference in the highest value and the lowest value in that dataset.

The interquartile range is the difference in the lower and upper quartiles (data points that lie 1/4 and 3/4 into the dataset respectively).

Yes. The normal idea of "range" is the difference between the highest value and the lowest value in a set of data. It gives an idea of the spread of the data, the variability if you like. But that indicator of "range" can be enormously exaggerated if you have even a single (or several) unusual data item(s), which are either very high or very low compared to all the others. The Interquartile Range ignores the top 25% of the data and the bottom 25% as well, and looks at the spread of just the middle 50%. Using the IQR can be very useful when comparing two sets of data.

Yes! A normal range is the maximum minus the minimum, whereas an interquartile range is the upper quartile minus the lower quartile.

Yes, the interquartile range (IQR) and normal range are quite different; think of the IQR like the "middle chunk" of your data - it looks at where the middle 50% of all your values fall by finding the difference between the 75th and 25th percentiles.

The normal range, on the other hand, goes wider - it captures about 95% of the data and is calculated by subtracting the smallest value from the largest.

Here's a simple example:

If we have these numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9

IQR = 4 (from 3 to 7)

Range = 8

Yes, the range is the distance from the highest value to the lowest value. The Inter-Quartile Range is quite literally just the range of the quartiles: the distance from the largest quartile to the smallest quartile, which is IQR=Q3-Q1.

Yes, the normal range of data is the greatest value in the data set minus the smallest value in a data set whereas the interquartile range is the upper quartile minus the lower quartile. Remember that normal range uses all anomalous/extreme values of data!

Yes, the interquartile range and "normal range" are different. For example, imagine a maths test taken by 100 people. The lower quartile is the score achieved by the person with the 25th lowest score, and the upper quartile the score achieved by the person with the 75th lowest score. The interquartile range is the difference between their score. The "normal range" would be the difference in score between the person with the best score, and the person with the lowest score.

Note that the "normal range" is often just called the range.

Yes. The range is the difference between the biggest and smallest number in the list. The interquartile range uses quarters (hence the word quartiles). Find the numbers that are at the 1/4 and the 3/4 position of the list. Then find the difference between these. The interquartile range is useful especially when the data has outliers.

They are very similar but slightly different:

Range: The difference between the largest and smallest values in the set of numbers

Interquartile range [IQR]: the difference between the upper and lower quartile, where the four quartiles split the data into even quarters

Example:

1,1,3,4,6,7,8,9,10

Range = 10 - 1 = 9

IQR: Q3 [upper quartile] = 8.5, Q1 [lower quartile] = 2

IQR = 8.5-2 = 6.5