grouped data and ungrouped data

GROUPED DATA

1 - . Their purpose is to summarize the information.

. 2 - Generally, the elements are larger and therefore need to be grouped , this means : sort , classify and express in a frequency table .

. 3 - data is grouped , if you have 20 or more items. Even though we have more than 20 items, you must verify the data of n are material, This is the information is " repetitive " , we must also verify that the data can be classified . And that this classification has coherence and logic (according to what we are asking ) .
Once we have ordered and classified , will present information obtained through a " frequency table "

. 4 - Grouping the data can be simple or by class intervals .



DATA NOT A GRUPADOS .

1 - . Is raw data ( ie occur unclassified )

. 2 - No need to classify or generate a table of frequent, because it has " a lot of sense ."

3 - . Smaller items ( usually less than 20 items ) This does not happen always . .
Aunnque count with less than 20 items , you should verify that the data is not significant , this is information that is not " repetitive " , thus we know that can not be classified and therefore be summarized in a "sliding frequency . "
Where once we sort the items , we count with meaningful data. We proceed to classify (if possible , since we must also seek to classify logic elements ) to become " grouped data " .

For example :

* If we were asked to obtain information from the territory of each of the states of Mexico . It makes little sense that " we try to group " , as only asks us the name of the state of the Mexican Republic and the territorial extension. For that we would need a frequency table of 32 elements , when they are repeated only 1 time ?


4 - . Ungrouped data can also be ordered and in the same way , can also be obtained graphs, determine mean, standard deviation , etc. .
The fact that the data " ungrouped " can be ordered , does not mean that they become " grouped data " .
Examples:
You'll investigate the age group of 20 children in ungrouped data (ie , 20 children come and you also get age so the write down

2,2,1,3,3,3,4,4,5,6,1,2,2,3,3,3,4,4,3,6 (Total 20 children )
These data are not grouped why not have qualified and counted

1,1,2,2,2,2,3,3,3,3,3,3,3,4,4,4,4,5,5,6 (Total 20 children )
The ungrouped data can also be ordered , for example less than the older age are not counted or ranked are only sorted

To be pooled data you have to count and classify , for example how many children were in each year. (and still are 20 children )

Age .......... Frequency
1 .................. 2
2 .................. 4
3 .................. 7
4 .................. 4
5 .................. 2
6 .................. 1
Total ............ 20

or can also be grouped (pooled Series ) classes , ranges, groups or ranges eg 2 years for this case (and still 20)

Age .......... Frequency
1-2 ............... 6
3-4 ............... 11
5-6 ............... 3
Total ............. 20


YOU CAN CHECK THE FOLLOWING REFERENCES .
" statistics " , Murray R. Spiguel
Editorial schaum . second Edition

* Applied Statistics SOTY , NORBERTO Guarin Salazar
* " STATISTICAL FOOTSTEPS " Howard B. Christensen