====== QC2d-4 Statistics control Mean Value Method ======


==== Description of Method ==== 

The arithmetic mean value of 30 days observations M is calculated. 
Day d is the date 15 days prior to present.
Daily station specific normal values is extracted from the climate database. The value M' is the normal value of day d.

Corresponding values at three neighbour stations are Mn1, Mn2, Mn3.
Corresponding reference normal value at three neighbour stations are Mn'1, Mn'2, Mn'3.

An error is detected when

<nowiki>| M - M' | > tol1</nowiki>

and at least two of the three following inequalities are satisfied

<nowiki>| Mn1 - Mn'1 | < tol1</nowiki>

<nowiki>| Mn2 - Mn'2 | < tol1</nowiki>

<nowiki>| Mn3 - Mn'3 | < tol1</nowiki>

where tol1 is a tolerance value

==== Quality Control Level ====

  * QC2d-4


==== Run Parameters ====

It shall be possible to run the algorithm for

  * TA
  * PR

==== Characteristics of the data to which the method is applied ====

__CONTROLINFO AND/OR USEINFO__

  * none
 
__TYPEID, OTHER METADATA__

  * all typeid

==== Flag Settings ====

__SPECIFICATION OF CONTROLFLAGS TO BE SET FOR EXPECTED RESULTS OF THE ALGORITHM, I.E. CONSIDER BOTH POSITIVE AND NEGATIVE RESULTS__

  * fstat=1 on no error detection
  * fstat=2 on error detection


__EXPECTIONS OF THE USEINFO FLAGS CORRESPONDING TO CONTROLINFO FLAG SETTINGS__

  * fstat=2 -> useinfo(2)=2


==== Dependencies ====

  * Definition of neighbor stations
  * Definition of regional reference stations when normal values is unavailable
  * Extracts from KDVH