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Topic: Interquartile range

In the News (Sun 16 Jun 19)

  Stats: What is an interquartile range?
The interquartile range (IQR) is the distance between the 75
The IQR is essentially the range of the middle 50% of the data.
Select halfway between the 11th and 12th observations (4.80 and 5.26) and halfway between the 3rd and 4th observations (3.49 and 3.68).
www.childrens-mercy.org /stats/definitions/iqr.htm   (122 words)

  Establishing the arm's length price: gathering your own evidence
The median is the mid-point of the interquartile range.
The mid-point, or median of the interquartile range is 4.8%.
The mid-point or median of the interquartile range is 4.7%.
www.hmrc.gov.uk /manuals/intmanual/INTM467150.htm   (1360 words)

 Interquartile range - Wikipedia, the free encyclopedia
In descriptive statistics, the interquartile range (IQR) is the difference between the third and first quartiles and is a measure of statistical dispersion.
The interquartile range is a more stable statistic than the range, and is often preferred to that statistic.
The interquartile mean is a measure of central tendency.
en.wikipedia.org /wiki/Interquartile_range   (212 words)

 Semi-Interquartile Range
The semi-interquartile range is a measure of spread or dispersion.
Since half the scores in a distribution lie between Q3 and Q1, the semi-interquartile range is 1/2 the distance needed to cover 1/2 the scores.
The semi-interquartile range is little affected by extreme scores, so it is a good measure of spread for skewed distributions.
davidmlane.com /hyperstat/A48607.html   (147 words)

 Learning Resources: Statistics: Power from Data! Range and quartiles
The range is an informative tool used as a supplement to other measures such as the standard deviation or semi-interquartile range, but it should rarely be used as the only measure of spread.
The interquartile range is another range used as a measure of the spread.
The interquartile range spans 50% of a data set, and eliminates the influence of outliers because, in effect, the highest and lowest quarters are removed.
www.statcan.ca /english/edu/power/ch12/range.htm   (772 words)

 VIAS Encyclopedia: Interquartile Range   (Site not responding. Last check: 2007-10-26)
As with the mean and the standard deviation, distributions can also be described by the median and a range of fractiles around the median.
The interquartile range (IQR) in particular is used to describe the dispersion of the data.
The interquartile range (IQR) is defined as the range between the first and the third quartile.
www.vias.org /encyclopedia/cc_iqr.html   (102 words)

 Interquartile range   (Site not responding. Last check: 2007-10-26)
In descriptive statistics the interquartile range (IQR) is the difference between the third first quartiles.
The interquartile range is a more statistic than the range and is usually preferred to that
Since 25% of the data are less or equal to the first quartile and are greater than or equal to the quartile the difference is the length of interval that includes about half of the This difference should be measured in the units as the data.
www.freeglossary.com /Interquartile_Range   (406 words)

The interquartile range (IQR) is a range that contains the middle 50% of the scores in a distribution.
For Quiz 1, the 75th percentile is 8 and the 25th percentile is 6.
Using this terminology, the interquartile range is referred to as the H-spread.
psych.rice.edu /notestat/chapter3/variability.html   (1025 words)

 [No title]
The interquartile range is the distance between the 1st and 3rd quartiles (25th and 75th percentiles).
The range is a crude measure of variability which is only effected by changes to two scores but if one of those changes drastically, the range is also drastically changed even though the rest of the distribution is unchanged.
The interquartile range and semi-interquartile range are compromises between the crudeness of the range and the over-sensitivity of the standard deviation.
www.andrews.edu /~thayerj/EDRM611/Summer2001ObjectivesUnit4.htm   (1852 words)

 1.5 Exploratory Data Analysis (EDA)
The range for any set of data measured on ordinal scales on up is just the maximum score minus the minimum score.
For qualitative variables measured on nominal scales the range is the number of categories having at least one entry.
By definition the semi-interquartile range is half the interquartile range, or half the height of the box.
www.uth.tmc.edu /uth_orgs/educ_dev/oser/L1_5.HTM   (935 words)

 Algorithms   (Site not responding. Last check: 2007-10-26)
Concentration is measured as the number of bins (converted to the appropriate time or frequency units) needed to accumulate a fraction P of the total signal energy in the sorted energy distribution.
Lower-upper skewness measures the asymmetry of the lower-upper range in relation to the median of the straight distribution.
As with the percentile measures (median, interquartile range, and percentile skewness), the concentration, lower-upper range, and lower-upper skewness can be measured for each short-time spectrum and narrow-band envelope composing the spectrogram, generating the corresponding time or frequency contours.
www.birds.cornell.edu /BRP/research/algorithms/RSM.html   (1828 words)

 Reading Statistics and Research (Schuyler Huck): Student Help
Because of its name, the semi-interquartile range is thought to be something horrid by many, many students who are taking their first course in statistics.
Thus, it is like a range, a standard deviation, or a variance in that it measures the degree of "spread" among a group of scores.
Like other measures of variability, the SIQR will be 0 if all the scores are the same; it will be larger than zero to the extent that the scores are spread out from each other.
www.readingstats.com /fourth/email2b.htm   (528 words)

 Range   (Site not responding. Last check: 2007-10-26)
The range of a set of numbers is from the minimum value to the maximum.
Whilst this provides the extent of the data, it may not be a "robust" measure as the extreme values may be "rogues" or "outliers" and not representative of the object of study.
The interquartile range indicates the "typical" condition where the windspeed will be betwenn 7.3 and 11.0 for 50% of the time.
www.brighton-webs.co.uk /Statistics/range.asp   (168 words)

 BBC - GCSE Bitesize - Maths | Data handling: intermediate/higher | The interquartile range
The interquartile range is the difference between the upper quartile and the lower quartile.
Therefore the interquartile range is 4 - 1 = 3.
In cases such as these it is often preferable to use the interquartile range when comparing the data.
www.bbc.co.uk /schools/gcsebitesize/maths/datahandlingih/01tendencyspreadihrev5.shtml   (257 words)

 Interquartile mean - Wikipedia, the free encyclopedia
The interquartile mean (IQM) is a statistical measure of central tendency, much like the mean (in more popular terms called the average), the median, and the mode.
The IQM is a truncated mean and so is very similar to the scoring method used in sports that are evaluated by a panel of judges: discard the lowest and the highest scores; calculate the mean value of the remaining scores.
Like the median, the IQM is insensitive to outliers; in the example given, the highest value (38) was an obvious outlier of the dataset, but its value is not used in the calculation of the IQM.
en.wikipedia.org /wiki/Interquartile_mean   (734 words)

 Page 2
The range is the simplest measure of dispersion to calculate.
Another disadvantage of using the range as a measure of dispersion is that its calculation is based on two values only: the largest and the smallest.
The interquartile range measures the spread of the middle 50 percent of a group of scores.
www.ualr.edu /lcpearson/statistics/basic/week04/page2.htm   (4358 words)

 SurfStat.australia   (Site not responding. Last check: 2007-10-26)
The range is the difference between the lowest value and the highest value: the maximum minus the minimum.
The range depends only on the extreme values in the data set.
A measure of the spread of data which is not so much affected by extreme values as the range is to take values 5% in from either end, or 1/4 in from either end.
www.anu.edu.au /nceph/surfstat/surfstat-home/1-2-3.html   (436 words)

 Measures of Position
The interquartile range is the difference between the quartiles.
The midquartile range is the midpoint between the quartiles.
The 10-90 percentile range is the difference between the 90th and 10th percentiles.
www.richland.edu /james/ictcm/2001/descriptive/helpposition.html   (599 words)

 Interquartile Range
The interquartile range is used as a robust measure of scale.
The interquartile range is less effected by extremes than the standard deviation.
www.itl.nist.gov /div898/software/dataplot/refman2/auxillar/iqrange.htm   (165 words)

 Interquartile Range   (Site not responding. Last check: 2007-10-26)
Q1 and Q3 = the lower and upper limit of the interquartile range.
The interquartile range = Q3 - Q1 Q1 = the 25th percentile.
Therefore, the interquartile range (usually denoted as IQR) contains 50% of the observations.
probabilitynet.com /iqr.htm   (96 words)

 Biostatistics for the Clinician
The interquartile range, then, from the 25th percentile to the 75th percentile, includes 50% of the values in the sample.
The interquartile range is the distance between the 25th percentile and the 75th percentile.
The interquartile range is a measure of variability that can be appropriately applied with ordinal variables and therefore may be used especially in conjunction with non-parametric statistics (see Figure)..
www.uth.tmc.edu /uth_orgs/educ_dev/Web_Sites/workint/sampinst.html   (3993 words)

 Research Methods - Measures of Variability in AllPsych Online
There are four major measures of variability, including the range, interquartile range, variance, and standard deviation.
The interquartile range, on the other hand, measures the difference between the outermost scores in only the middle fifty percent of the scores.
percentile, representing the range of the middle 50 percent of scores.
allpsych.com /researchmethods/variability.html   (271 words)

 Math Forum - Ask Dr. Math   (Site not responding. Last check: 2007-10-26)
Interquartile range: the difference between the upper and lower quartiles.
Let's look at a set of data and explain these four points of emphasis: 25, 26, 27, 28, 29, 30, 40, 41, 42 The median is to be found first.
I hope that this will help you better understand the concept of interquartile range.
www.forum.swarthmore.edu /dr.math/problems/newton.10.27.99.html   (357 words)

 Air Travel Demand Elasticities: Concepts, Issues and Measurement: 2
The median elasticity is —1.52 with estimates distributed across the range of values with little crowding.
The range for 1997-02 studies is -0.5 to —1.4 while the range for 1992-97 studies is —0.3 to —1.2.
The estimates are distributed between a range of —0.4 and —2.37.
www.fin.gc.ca /consultresp/Airtravel/airtravStdy_2e.html   (3283 words)

 Further education lesson trader
measures of dispersion - range, semi interquartile range, mean deviation, variance, standard deviation
As a site we are affiliated with amazon.co.uk which enables us to offer a huge range of books videos and learning aids.
At present we are trying to match textbooks and general interest books to the various subjects we have on the site, we hope this will be of assistance to you when searching for resources.
www.furthereducationlessontrader.co.uk   (998 words)

 PinkMonkey.com Statistics Study Guide 5.8 Quartiles And Interquartile Range
If we concentrate on two extreme values (as in the case of range), we don’t get any idea about the scatter of the data within the range (i.e.
For this reason the concept of interquartile range is developed.
It is the range which includes middle 50% of the distribution.
www.pinkmonkey.com /studyguides/subjects/stats/chap5/s0505801.asp   (185 words)

 Vary Useful Statistics
When summarising a dataset, at least two measures are needed - one to locate the dataset and another to indicate the spread of the data.
The mean and the median are the common measures of location, while the standard deviation and interquartile range are commonly used to summarise the spread of the data.
The interquartile range, while simple in concept, has caused much grief to introductory statistics teachers since different respectable sources define it in different respectable ways!
exploringdata.cqu.edu.au /spread.htm   (355 words)

 Measures of Variability
The highest number is 99 and the lowest number is 23, so 99−23=76; the range is 76.
It is computed as follows: IQR=75th percentile−25th percentile For Quiz 1, the 75th percentile is 8 and the 25th percentile is 6.
This work is licensed by David Lane under a Creative Commons License.
cnx.org /content/m10947/latest   (994 words)

 Ch2 Distributions Pt 2
Thus for our 12 exam scores, the range extends from a low of 61 to a high of 97, and the interquartile range extends from a low of 76 to a high of 86.
In effect, "plus or minus" one standard deviation represents a range within the distribution, centered upon the mean.
Unlike the analogous interquartile range, however, the range between
faculty.vassar.edu /lowry/ch2pt2.html   (1396 words)

 NEJM -- Antiretroviral Therapy in a Thousand Patients with AIDS in Haiti
26 percent (interquartile range, 22 to 36 percent) at 12 months.
range, 8 to 20 percent) to 21 percent (interquartile range,
a median of 5.5 kg (interquartile range, 1.4 to 10.5).
content.nejm.org /cgi/content/full/353/22/2325   (3768 words)

 Interquartile Range
What iam investigating is whether i should use interquartile range in a safety stock calculation instead of stdev when the distribution is not normal.
Interquartile Range by slimboy on Sunday, 25th June 2006
Re: Interquartile Range by slimboy on Monday, 26th June 2006
www.isixsigma.com /forum/showmessage.asp?messageID=96139   (213 words)

 Site Map
Variability - Quartiles - Quartile Deviation - Semi Interquartile Range - Quartile Range
Continuous Distributions - Beta Distribution - Notation - Range - Parameters
Continuous Distributions - Cauchy 1 (Parameter) Distribution - Range
www.xycoon.com /toc.htm   (3938 words)

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