POSITION MEASURES

POSITION MEASURES

1. Position measures divide a data set into groups with the same number of individuals. To calculate the position measures it is The data must be ordered from smallest to largest.

2. QUARTILES

   • The quartiles are the three values ​​that divide the set of data sorted into four percentage parts same. There are three quartiles usually denoted Q1, Q2, Q3. The second quartile is precisely the median. The first quartile is the value at or below the which remains a quarter (25%) of all the values ​​of the succession (ordered); the third quartile, is the value in the which or below which are three-fourths (75%) of the data.
     • GROUPED DATA
       • Since the quartiles become most important when we count a large number of data and take into account that in these cases the data are generally summarized in a frequency table. The formula for calculating the quartiles when it comes to grouped data is as follows: k= 1,2,3 Where: Lk = Lower real class limit of quartile k n = Number of data Fk = Cumulative frequency of the class which precedes the class of quartile k. fk = Frequency of the class of quartile k c = Interval length of the class of quartile k If we want to calculate each quartile individually, using another formula we have the following: The first quartile Q1, is the smallest value that is greater than a quarter of the data; namely, that value of the variable that exceeds 25% of the observations and is exceeded by 75% of the observations.
     • NON-GROUPED DATA

3. DECILES

   • Deciles are certain numbers that divide the sequence of data ordered in ten parts percentage equal. They are the nine values ​​that divide the ordered data set into ten equal parts, are also a particular case of the percentiles. The deciles are denoted D1, D2,…, D9, which read first decile, second decile, etc. The deciles, like quartiles, they are widely used to assess academic achievement.
     • GROUPED DATA
     • NON-GROUPED DATA

4. PERCENTILE

   • Percentiles are perhaps the most widely used measures for purposes of locating or classifying people when they attend to characteristics such as weight, height, etc Percentiles are certain numbers which divide the sequence of ordered data into one hundred equal percentage parts. These are the 99 values which divide the data set into 100 equal parts organized. The percentiles (P1, P2,... P99), read first percentile,…, percentile 99.
     • GROUPED DATA
     • NON-GROUPED DATA

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