Difference between revisions of "Documentation/How Tos/Calc: DVAR function"

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:The '''[[Documentation/How_Tos/Calc: Database functions|Database functions overview]]''' describes these parameters in detail.
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:The * [[Documentation/How_Tos/Calc: Database functions|Database functions overview]]''' describes these parameters in detail.
  
  
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<tt>'''DVAR'''</tt> returns the '''bias-corrected sample variance''', which assumes that the chosen rows of the <tt>'''database_table'''</tt> contain a random sample of a normally distributed population. If the chosen data are the entire population, use '''<tt>[[Documentation/How_Tos/Calc: DVARP function|DVARP]]</tt>''' instead. The <tt>'''DVAR'''</tt> calculation uses this formula:
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<tt>'''DVAR'''</tt> returns the '''bias-corrected sample variance''', which assumes that the chosen rows of the <tt>'''database_table'''</tt> contain a random sample of a normally distributed population. If the chosen data are the entire population, use '''<tt>* [[Documentation/How_Tos/Calc: DVARP function|DVARP]]</tt>''' instead. The <tt>'''DVAR'''</tt> calculation uses this formula:
  
 
<center>[[Image:Calc_sample_var_formula.png]]</center>
 
<center>[[Image:Calc_sample_var_formula.png]]</center>
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Simply put, variance is a measure of how widely spread data values are. It is the square of the <i>standard deviation</i> (see '''<tt>[[Documentation/How_Tos/Calc: DSTDEV function|DSTDEV]]</tt>''', '''<tt>[[Documentation/How_Tos/Calc: DSTDEVP function|DSTDEVP]]</tt>'''). Variance is a reliable measure only if there is enough data to examine.
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Simply put, variance is a measure of how widely spread data values are. It is the square of the <i>standard deviation</i> (see '''<tt>* [[Documentation/How_Tos/Calc: DSTDEV function|DSTDEV]]</tt>''', '''<tt>* [[Documentation/How_Tos/Calc: DSTDEVP function|DSTDEVP]]</tt>'''). Variance is a reliable measure only if there is enough data to examine.
  
  
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=== See also: ===
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{{Documentation/SeeAlso|
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'''[[Documentation/How_Tos/Calc: DCOUNT function|DCOUNT]]''',
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* [[Documentation/How_Tos/Calc: DCOUNT function|DCOUNT]]
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'''[[Documentation/How_Tos/Calc: DCOUNTA function|DCOUNTA]]''',
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* [[Documentation/How_Tos/Calc: DCOUNTA function|DCOUNTA]]
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'''[[Documentation/How_Tos/Calc: DSUM function|DSUM]]''',
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* [[Documentation/How_Tos/Calc: DSUM function|DSUM]]
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'''[[Documentation/How_Tos/Calc: DPRODUCT function|DPRODUCT]]''',
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* [[Documentation/How_Tos/Calc: DPRODUCT function|DPRODUCT]]
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'''[[Documentation/How_Tos/Calc: DMAX function|DMAX]]''',
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* [[Documentation/How_Tos/Calc: DMAX function|DMAX]]
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'''[[Documentation/How_Tos/Calc: DMIN function|DMIN]]''',
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* [[Documentation/How_Tos/Calc: DMIN function|DMIN]]
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'''[[Documentation/How_Tos/Calc: DAVERAGE function|DAVERAGE]]''',
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* [[Documentation/How_Tos/Calc: DAVERAGE function|DAVERAGE]]
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'''[[Documentation/How_Tos/Calc: DSTDEV function|DSTDEV]]''',
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* [[Documentation/How_Tos/Calc: DSTDEV function|DSTDEV]]
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'''[[Documentation/How_Tos/Calc: DSTDEVP function|DSTDEVP]]''',
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* [[Documentation/How_Tos/Calc: DSTDEVP function|DSTDEVP]]
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'''[[Documentation/How_Tos/Calc: DVARP function|DVARP]]''',
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* [[Documentation/How_Tos/Calc: DVARP function|DVARP]]
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'''[[Documentation/How_Tos/Calc: DGET function|DGET]]'''
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* [[Documentation/How_Tos/Calc: DGET function|DGET]]'''
  
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'''[[Documentation/How_Tos/Calc: VAR function|VAR]]''',
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* [[Documentation/How_Tos/Calc: VAR function|VAR]]
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'''[[Documentation/How_Tos/Calc: VARP function|VARP]]'''
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* [[Documentation/How_Tos/Calc: VARP function|VARP]]'''
  
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'''[[Documentation/How_Tos/Calc: Database functions#Overview|Database functions overview]]'''
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* [[Documentation/How_Tos/Calc: Database functions#Overview|Database functions overview]]'''
  
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'''[[Documentation/How_Tos/Calc: Database functions|Database functions]]'''
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* [[Documentation/How_Tos/Calc: Database functions|Database functions]]'''
  
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[[Documentation/How_Tos/Calc: Functions listed alphabetically|'''Functions listed alphabetically''']],
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* [[Documentation/How_Tos/Calc: Functions listed alphabetically|Functions listed alphabetically]]
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[[Documentation/How_Tos/Calc: Functions listed by category|'''Functions listed by category''']]
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* [[Documentation/How_Tos/Calc: Functions listed by category|Functions listed by category]]}}
  
 
==Issues==
 
==Issues==

Revision as of 13:45, 25 February 2009


DVAR

Returns the bias-corrected sample variance of values in a column of a Calc 'database' table, in rows which meet specified criteria.


Syntax:

DVAR(database_table; field; criteria_table)

where

database_table is a range defining the data to be examined.
field is the column to examine. It may be a column number (1 is the first column of the database table, 2 is the second ...) or a column header (enclosed in quotation marks ””) or a cell referring to a column header.
criteria_table is a range containing criteria, which are used to select which rows of the database_table to examine.


The * Database functions overview describes these parameters in detail.


DVAR returns the bias-corrected sample variance, which assumes that the chosen rows of the database_table contain a random sample of a normally distributed population. If the chosen data are the entire population, use * DVARP instead. The DVAR calculation uses this formula:

Calc sample var formula.png

where N is the number of values included and xi are those values.


DVAR ignores any cell containing text in the field column.


Simply put, variance is a measure of how widely spread data values are. It is the square of the standard deviation (see * DSTDEV, * DSTDEVP). Variance is a reliable measure only if there is enough data to examine.


Example:

In this spreadsheet:

  A B C D E
1 Name Grade Age Distance to School Weight
2 Andy 3 9 150 40
3 Betty 4 10 1000 42
4 Charles 3 10 300 51
5 Daniel 5 11 1200 48
6 Eva 2 8 650 33
7 Frank 2 7 300 42
8 Greta 1 7 200 36
9 Harry 3 9 1200 44
10 Irene 2 8 1000 42
11          
12          
13 Name Grade Age Distance to School Weight
14   2      


DVAR(A1:E10; "Weight"; A13:E14)

returns the bias-corrected sample variance of the weights of children in the second grade. This is not a useful measure, as there are so few children.


Template:Documentation/SeeAlso

Issues

  • The OOo2.3 Help implies that 0 as a field will include the entire database table. This seems to be wrong - only the variance of a single column can be found.
  • Logical values TRUE and FALSE are interpreted as 1 and 0 in the calculation. This is not compatible with Excel, which ignores logical values. This will very rarely cause difficulty.
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