10 Replies Latest reply on Nov 8, 2019 2:37 PM by Kaz Shakir

    Pre and Post Test Viz

    Tamara Becker


      I'm trying to create a visualization but having trouble getting the results I thought I wanted.


      I have 26 classes with ~20 students in each class.

      There is a pre and post test with 10 questions that are exactly the same.

      The answers can be Strongly Agree, Agree, Neutral, or Disagree.


      We want to see how students change their  answers, if at all.


      The image below is is how I started but am willing to take any suggestions.

      Thanks in advance.


        • 1. Re: Pre and Post Test Viz
          Ken Flerlage

          I think we'll need to see some data or a workbook in order to be of much help with this one. Is that possible?

          • 2. Re: Pre and Post Test Viz
            Brian Cronin

            From what I see I would just start with a bunch of comparisons for example To see if answer changed:


            if [Askforhelp] = [askforhelp (Post Survey)] then "No Change" else "Changed"



            If you want to get more visual you'd probably have to figure out a way to convert your text to measures something like:


            Case [Ask for help]

            when 'Strongly Agree' then 5

            when 'Agree' then 4

            when 'Neutral' then 3

            when 'Disagree' then 2

            when 'Strongly disagree' then 1



            Then repeat for all questions and you can start doing comparisons to see the magnitude of change by subtracting this field from the field you create for the post-survey 


            Hope this gives you some help

            • 3. Re: Pre and Post Test Viz
              Kaz Shakir

              Tamara Becker,

              Can you share a little more information about the structure of your data?  For example, what does the "ID" field represent - is that the Student ID? or is it a question ID?  And then, what are three columns that follow - you said that the survey had 10 questions, and you have 20 students, so I would expect to see either 10 columns (one for each question on the survey), or 20 columns (one for each student), or I would expect to see just two columns, one for the question, and one for the answer (in addition to a column for the student id).


              If you can post the data, or a mock-up of the data, in an excel or csv file, that would be helpful as well.



              • 4. Re: Pre and Post Test Viz
                Tamara Becker

                I was tinkering with the idea of converting the responses to measures. 

                Your response has persuaded me to give it a try.

                Thank you.

                • 5. Re: Pre and Post Test Viz
                  Tamara Becker

                  I've attached my two Excel files.  This is for one class. 

                  • 6. Re: Pre and Post Test Viz
                    Kaz Shakir

                    Tamara Becker,

                    Thanks for posting the data.  That helps.


                    The first thing I would do is to convert the data to a "tall-and-thin" format (pivot the data).  If you take a look at the excel files I am attaching you will see what I mean about the format of the data.  Then you can bring both files into Tableau as a connection, and grab each of the new tables of information and join them together like so:


                    Next, I created a couple of new calculated fields, one to determine if the pre and post answers are the same, and another to count the number of students, like so:


                    Then, you could create a visual like this one (just as an example).  The Pre Answers are across the top, and the corresponding Post Answers are across the bottom; and the yellow bar indicates the answers that remained the same, while the green bars indicate answers that changed.  So, for example, across all questions, only 9 students who strongly agreed on the pre-survey, also strongly-agreed on the post-survey; while 2 students who marked Strongly Agree on a question on the pre-survey changed their answers to Strongly Disagree on the post survey.  While this is interesting across all questions, you probably want to focus in question by question, so you can use the filter on the side to select the question, and the chart will update.


                    Is that the kind of thing you are trying to achieve?  Please let us know if this solves your situation.



                    • 7. Re: Pre and Post Test Viz
                      Tamara Becker


                      This is very different (in a good way) then my original blurry vision --which I didn't explain that well because it wasn't clear to me. Now with your idea, I can see that we would like to have more detail how students changed their answers, for example more disagreement, more agreement, or staying the same.


                      • 8. Re: Pre and Post Test Viz
                        Kaz Shakir

                        Tamara Becker,

                        Well that's certainly possible.  Here's a possible approach:


                        1. Create calculated fields to place a numerical value on the answers:


                        2. And then create a calculated measure to determine the change in sentiment:


                        3. Then you could create a viz like this to show how sentiment changed by question:

                        And when you hover over the circle, you can see the details of the student id, and how they changed their answer from pre to post.



                        • 9. Re: Pre and Post Test Viz
                          Tamara Becker

                          Yes! Yes! Yes!  This is it! I love it!

                          Thanks a million Kaz!

                          • 10. Re: Pre and Post Test Viz
                            Kaz Shakir

                            What a great reaction!!  Great way to end my week.

                            You're welcome.  Have a great weekend.