User spesifies whether the subject is male or female (male is default value), he tells the height in centimetres and age in years. Then the calculator produces the approximate reference value for PEF or Peak Expiratory Flow (ie how fast one should be able to exhale). The calculated PEF-value should be also converted to a different value using another reference value standard,
User spesifies 2 different measured PEF-values and the calculator calculates the change between the 2. (Used to see whether the person has daily spontaneus difference in values or whether using medication produces enough improvement in PEF-values).
User spesifies the best measured PEF-value for a patient and then the user chooses between 3 choices (or radio buttons). 85 %, 70 % or 50 %. The calculator determines how much the choice is from the original value and produces a different text regarding the three radio buttons.
Attached is a sample Excel sheet which shows the basic function of the calculator and also the needed formulas. Basically the formulas use basic mathematical operators. The most difficult part of the code is the first calculator which should have only 3 user-spesified-field (sex, age, height) and fourth defining the PEF-value. If the explanation was unclear please ask for more detail.
The design of the calculator is not a big problem. You can see the site where the calculator will be placed at www.gfr.fi If needed I will do the design formatting but if you can design the calculator to be fitted in the spesified website I will be more impressed.