I use this example to illustrate one approach. I follow the instructions up to step 7. Then from the red triangle menu of the report, I choose "Save Columns" > "Prediction Formula". Now I get a new column, and the formula is the function of the curve. Copy the formula from the column.
Now go to Scripting Index, and find "Integrate" function.
![peng_liu_1-1631762883318.png peng_liu_1-1631762883318.png](https://community.jmp.com/t5/image/serverpage/image-id/35852i2FE6BCA02301B5C4/image-size/medium?v=v2&px=400)
Now paste the formula and replace the highlighted part, get this:
![peng_liu_2-1631762981590.png peng_liu_2-1631762981590.png](https://community.jmp.com/t5/image/serverpage/image-id/35853i981E93B8AA9A7454/image-size/medium?v=v2&px=400)
Now remove all the colon symbols, by replacing colon by empty string.
![peng_liu_3-1631763183428.png peng_liu_3-1631763183428.png](https://community.jmp.com/t5/image/serverpage/image-id/35854i8FCD7A8DDEBB9C46/image-size/medium?v=v2&px=400)
Also replace "x" by "age", my x variable name.
Now decide where the upper limit of the integration (100%), say 80. And the result is 69.783 for 100%.
![peng_liu_5-1631763270010.png peng_liu_5-1631763270010.png](https://community.jmp.com/t5/image/serverpage/image-id/35856i9285E4DB7A646E5D/image-size/medium?v=v2&px=400)
Now the task is to find a number to replace 80, and give me 50%: 69.783/2=34.8915. I got 44.228 after maybe a dozen try and error.
![peng_liu_6-1631763432932.png peng_liu_6-1631763432932.png](https://community.jmp.com/t5/image/serverpage/image-id/35857iED72FE1B7223CAE5/image-size/medium?v=v2&px=400)
It requires JSL programming, but not much, to get more precise result quickly. Mostly still copy and paste. See the following screenshot.
![peng_liu_9-1631764338721.png peng_liu_9-1631764338721.png](https://community.jmp.com/t5/image/serverpage/image-id/35860i35CEB26C3BD53D54/image-size/medium?v=v2&px=400)
The key is to find the value that minimize the squared difference between integral and the target value 34.8919. So I wrap the difference between integral and the target inside of a square, then call minimize function. Check out the function documentation for the syntax. The result for 50% is 44.226900491921.