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 Post subject: 10th Percentile?Posted: Sun, 13 May 2012 15:41:27 UTC
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STATISTICS: The interquartile range is given by
IQR = Q3 - Q1, where Q1 is the lower quartile, and it falls above 25% of the data, and Q3 is the upper quartile, and this falls above 75% of the data

To get the quartiles, the easy way is to find the median, and then split the data like that

For example, we have the values:
-17.5, 2.8, 3.2, 13.9, 14.1, 25.3, 45.8

The median is 13.9

Now, we split up the data into two halves from this number, and when the median is odd, we include the median in both halves:

lower half: -17.5, 2.8, 3.2, 13.9
upper half: 13.9, 14.1, 25.3, 45.8

So then, we get the median of the data (ex. lower half) and we will get the quartile (Ex. if we get the median for the lower half of the data, we get the Q1, or lower quartile, or the 25th percentile)

My question is: How would I get the 10th percentile, which is the number that falls above 10% of the data values?

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 Post subject: Re: 10th Percentile?Posted: Sun, 13 May 2012 16:00:07 UTC
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Joined: Mon, 29 Dec 2008 17:49:32 UTC
Posts: 6815
Location: On this day Taiwan becomes another Tiananmen under Dictator Ma.
A-R-Q wrote:
STATISTICS: The interquartile range is given by
IQR = Q3 - Q1, where Q1 is the lower quartile, and it falls above 25% of the data, and Q3 is the upper quartile, and this falls above 75% of the data

To get the quartiles, the easy way is to find the median, and then split the data like that

For example, we have the values:
-17.5, 2.8, 3.2, 13.9, 14.1, 25.3, 45.8

The median is 13.9

Now, we split up the data into two halves from this number, and when the median is odd, we include the median in both halves:

lower half: -17.5, 2.8, 3.2, 13.9
upper half: 13.9, 14.1, 25.3, 45.8

So then, we get the median of the data (ex. lower half) and we will get the quartile (Ex. if we get the median for the lower half of the data, we get the Q1, or lower quartile, or the 25th percentile)

My question is: How would I get the 10th percentile, which is the number that falls above 10% of the data values?

Linearly interpolate --- -17.5 is ile, 2.8 is ile, so 10%ile is ...

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 Post subject: Re: 10th Percentile?Posted: Sun, 13 May 2012 16:00:48 UTC
 Member of the 'S.O.S. Math' Hall of Fame

Joined: Sat, 20 Nov 2010 21:17:02 UTC
Posts: 436
outermeasure wrote:
A-R-Q wrote:
STATISTICS: The interquartile range is given by
IQR = Q3 - Q1, where Q1 is the lower quartile, and it falls above 25% of the data, and Q3 is the upper quartile, and this falls above 75% of the data

To get the quartiles, the easy way is to find the median, and then split the data like that

For example, we have the values:
-17.5, 2.8, 3.2, 13.9, 14.1, 25.3, 45.8

The median is 13.9

Now, we split up the data into two halves from this number, and when the median is odd, we include the median in both halves:

lower half: -17.5, 2.8, 3.2, 13.9
upper half: 13.9, 14.1, 25.3, 45.8

So then, we get the median of the data (ex. lower half) and we will get the quartile (Ex. if we get the median for the lower half of the data, we get the Q1, or lower quartile, or the 25th percentile)

My question is: How would I get the 10th percentile, which is the number that falls above 10% of the data values?

Linearly interpolate --- -17.5 is ile, 2.8 is ile, so 10%ile is ...

Ok would I do this by hand or on the computer?

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 Post subject: Re: 10th Percentile?Posted: Sun, 13 May 2012 16:50:19 UTC
 Moderator

Joined: Mon, 29 Dec 2008 17:49:32 UTC
Posts: 6815
Location: On this day Taiwan becomes another Tiananmen under Dictator Ma.
A-R-Q wrote:
Ok would I do this by hand or on the computer?

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