Exclude certain rows in data analysis

[#1]

I recently imported a survey that I created on Qualtrics.  The survey was 30 minutes long so some people stopped halfway through or at the beginning etc..  I gave each question a point value to make the survey like a test and assign grades.  But when I look at final points, this includes users who chose to terminate the survey early and do not have responses from that point forward.  How do I exclude them from my analysis?  I know this is confusing but I'd be happy to clarify.

[#2]

I would simply go to the last question(column) in your data table, right click on the cell in that column that did not choose to answer the question, and then select "Select Matching  Cells".  Then go to the far left of the data table, into the RowState column(the column that contains the row numbers), right click on one of the rows that was selected, and then choose, "Hide and Exclude".

Those rows that were selected will now be excluded from the analyses by the JMP Platforms.

Or you could create a subset of your data table.  To do this, go back to the RowState column and right click on one of the selected rows, and choose, "Invert Selection".  Then go to 

     Tables==>Subset

Choose in the dialog box that popped up, to use all columns, but to use only selected rows.  When you click on the OK, you will have a new table with just the individuals that completed the questionnaire

[#3]

Another thing that might work - assuming you created your "grades" using a formula, make sure the formula uses the Statistical Functions in the formula dialog.  For example, if you are creating an average score, don't manually enter the columns with a + sign, but use the Sum function (with the relevant columns to be summed as arguments).  These functions will ignore the blank cells and give you only the sum of the non-blank cells.  Then, if you divide by the Number function (which gives you the number of nonblank cells) you will get the average but only of the cells that have values.