You could create parameters and for these values and insert the parameter into your calculation instead of the fixed value.
If your membership type parameter was named Membership_Type_P, for example, your calculation would look like:
SUM(IF [Membership_Type] = [Membership_Type_P]
Do you have a sample workbook you are able to share? Happy to take a closer look if this isn't the solution you were looking for.
It doesn't have anything to do with your using Tableau Public, so that's good news!
I think what Tina's getting at is that you could create parameters, not create calculations. Click the small arrow alongside "Dimensions" on the left, and select "Create Parameter". Based on what you've said, it sounds like [Membership_Type] and [Rank by DogID] are both numeric fields. In the Create Parameter dialog box, name your first parameter something like Membership_Type_Prm and select "Data type:integer". Then select "Allowable values: List" and hit "Add from Field" to find the Membership_Type dimension. Once you select it, your list will be built using those dimensions as possible parameter choices. Follow a similar procedure for DogID. Now you can use these parameters in your calculations! The value of the parameter would be set to whatever the user selects. This saves you having to have much more complicated calculations. If you could post a mockup of your data set we could help set you in the right direction.
Thank you two for your advice, I finally managed to set up what I wanted.
You were both right, it is the parameter option what I need.
I just couldn't find where was the parameter option, because of the following picture I though that parameters where within the "calculated field option":
This is how I set up everything and it is just what I wanted:
Thank you again !!!