OK, we have two more use cases of calculated variables.
At present certain information is collected by diagnosis from the
inpatient and outpatient clinics. The malaria information is copied
to the malaria form, along with other information which does have to
be entered. We want to enter this information only once, from the
diagnosis records, but we want it to show up on the malaria form, we
think it's marginally acceptable to not show totals, but to not show
the malaria people "their" data is bad customer relations.
The clinics keep daily logs of birth control products dispensed, for
which the patients pay at a reduced rate. This form is turned in
along with the cash receipts, serving as a financial control. It
needs receipts by item (quantity x price) and total.
I think it would be good enough if the calculated variables were not
stored or aggregated and only existed while the dataset form was
being
displayed, for input or as a report. It would also be reasonable
to limit variables in the calculations to those in the dataset (so in
the malaria case, the variable would be in the dataset, it would not
appear on the form, only the calculated variable equal to its value).
Our users exist in a form-based world, where the form designers do
not
necessarily think systematically.
correspondence between the form and data entry/printing, we add to
their comfort with the system. While I may think the forms they are
using are don't make informatic sense, and that differences in
rendering call for different strategies on screens than on paper, I
can't impose these changes on them. Cross-foot totals do contribute
to accuracy in manual forms, they don't in computer forms; double
entry accounting contributes to accuracy in manual bookkeeping, it
doesn't in computer bookkeeping; but the habits of generations don't
change in a day.