Difference between revisions of "Durbin-Watson"

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  * if D < lower bound, positive correlation exists.
 
  * if D < lower bound, positive correlation exists.
 
  * if D is in between the two bounds, the test is inconclusive.
 
  * if D is in between the two bounds, the test is inconclusive.
 +
 +
==Example==
 +
{| class="wikitable"
 +
|+Spreadsheet
 +
|-
 +
! !! A !! B       
 +
|-
 +
! 1
 +
| 3 || 7 || 5 || 65 
 +
|-
 +
! 2
 +
| 4 || 3 || 7 || 38
 +
|-
 +
! 3
 +
| 5 || 5 || 8 || 51
 +
|-
 +
! 4
 +
| 6 || 8 || 1 || 38
 +
|-
 +
!5
 +
| 7 || 9 || 3 || 55
 +
|-
 +
!6
 +
| 8 || 5 || 4 || 43
 +
|-
 +
!7
 +
| 2 || 4 || 0 || 25
 +
|-
 +
!8
 +
| 3 || 2 || 6 || 33
 +
|-
 +
!9
 +
| 8 || 8 || 7 || 71
 +
|-
 +
!10
 +
| 9 || 6 || 4 || 51
 +
|-
 +
!11
 +
| 2 || 9 || 2 || 49
 +
|}

Revision as of 07:02, 3 May 2017

DURBINWATSONTEST(DataRange,ConfidenceLevel,NewTableFlag))


  • Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle DataRange} is the array of x and y values.
  • Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle ConfidenceLevel} is the value of alpha from 0 to 1.
  • Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle NewTableFlag} is either TRUE or FALSE. TRUE for getting results in a new cube. FALSE will display results in the same cube

Description

  • This function gives the test statistic of the Durbin-Watson test.
  • The test is used to detect the presence of autocorrelation in the residuals.
  • Autocorrelation means that adjacent observations are correlated.
  • If they are correlated, then least-squares regression underestimates the standard error of the coefficients.

Assumptions

The error terms are independent of each other.

  • The Durbin-Watson test uses the following statistic:

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle d=\frac{\sum_{i=2}^n (e_i-e_{i-1})^2)}{\sum_{i=1}^n (e_i)^2}}

  • where the Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle e_i = y_i-\bar{y_i}} are the residuals.
  • n is the number of elements in the sample.
  • k is the number of independent variables.
d takes the values between 0 and 4.
* d = 2 means there is no autocorrelation.
* A value substantially below 2 means that the data is positively autocorrelated.
* A value of d substantially above 2 means that the data is negatively autocorrelated.

Result

* if D > upper bound, no correlation exists.
* if D < lower bound, positive correlation exists.
* if D is in between the two bounds, the test is inconclusive.

Example

Spreadsheet
A B
1 3 7 5 65
2 4 3 7 38
3 5 5 8 51
4 6 8 1 38
5 7 9 3 55
6 8 5 4 43
7 2 4 0 25
8 3 2 6 33
9 8 8 7 71
10 9 6 4 51
11 2 9 2 49