Hello, In Manager, I do not understand the calculation of variables. I have a file with "birth date" and "date delivery" and "age" for the difference. and "weight" "size" and "BMI". When I click on the variable "Age" / edit / calculate, I can not find the variable "Age" for calculate the difference between two dates, but I see "BMI". On the other hand, on the variable "BMI" / edit / calculate, I do not find "BMI" but "Age" ..... Thank you for helping me.
Dear Bernard,
The reason that you cannot see the variables in this case is because the resulting field cannot be the field you are performing the calculation at.
Eg. if you wish to calculate the age, based on "birthdate" and "date delivery" and the result should be placed in the field "age", then:
1) Select the field "date delivery" 2) Go to calculations tab and select "Age" as the result variable 3) Select appropriate "birthdate" and "date delivery" fields. 4) Make sure you select "years" in 'save result as' 5) Optionally make the "age" field a No-enter field, such that the result cannot be manipulated during entry.
All calculations are done "after-entry", ie. after the field with the specified calculation has been entered a value, the result is calculated and put into the result field.
Regards, Torsten B. Christiansen EpiData
On 2014-03-06 09:11, epidata-list@lists.umanitoba.ca wrote:
Hello, In Manager, I do not understand the calculation of variables. I have a file with "birth date" and "date delivery" and "age" for the difference. and "weight" "size" and "BMI". When I click on the variable "Age" / edit / calculate, I can not find the variable "Age" for calculate the difference between two dates, but I see "BMI". On the other hand, on the variable "BMI" / edit / calculate, I do not find "BMI" but "Age" ..... Thank you for helping me.
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