1 2 Previous Next 22 Replies Latest reply on Aug 10, 2017 6:59 AM by Eric Mauser

# overlapping data points

Hi there,

I have a scatter plot representing correlation between two question scores on the likert scale (from 1 to 5). I want to show correlation between the two questions on an individual scale. Unfortunately, because the scores are whole numbers (1, 2, 3, 4, 5), the individual responses show up stacked directly on top of each other making the visual meaningless.

Does anyone know of a way to "jitter" the data points so they aren't overlapping - or an alternate way to visually present the correlation between scores?

Thanks for your help!

Katie

• ###### 1. Re: overlapping data points

What about making size the number of records? If you post a packaged workbook with your data I know others would help and respond as well.

• ###### 2. Re: overlapping data points

I suppose the challenge is that each data point represents an individual response, not a group of responses. One circle on that graph is really just one data point, but there are hundreds of other data points from individual responses underneath it…

Does that make sense?

Katie

• ###### 3. Re: overlapping data points

For example, you may have 30 responses at point (4,3) and just 10 responses at point (5,2) right?  So then if you size as the number of responses you’ll see that in the varying size of the circle. Can you drag the Tableau created measure “Number of Records” to Size? It would depend on how your data is structured. I’d need to see a packaged workbook to better understand and help out.

Thanks,

Michelle

• ###### 4. Re: overlapping data points

Thanks so much for your help, Michelle! Unfortunately the data is sensitive so I can’t share it as a packaged workbook.  The data is structured where each row is an a different person’s response. I sure did try dragging the “number of records” to size but it ends up looking exactly the same. It is calculating the total number of records for each person’s response individually, so I can’t even sum the number of records.

• ###### 5. Re: overlapping data points

Sounds like you have the detail too narrow. Remove “person” from the view. Try throwing just likert scale for q1 on columns and likert scale for q2 on rows.  Then Number of records as detail.

• ###### 6. Re: Re: overlapping data points

To size the circle, you need to change the data type from measure to dimension.

• ###### 7. Re: overlapping data points

I found this kb article and it shows the results of a survey question as a heat map. Not sure this gets to what you needed, but thought it might help: http://kb.tableausoftware.com/articles/knowledgebase/survey-data-grid-questions

I’ve attached a dummy workbook with this example as well.

• ###### 8. Re: overlapping data points

Thanks! From what my beginner eyes can tell, the situation is slightly different however we did find a similar work around that looks like this:

• ###### 10. Re: overlapping data points

Katie,

Sorry to be so late to the party.

I'm getting close to having a relatively easy solution to this.  Here's how it appears, at least so far.

I need to generate two random numbers and I'm not convinced the way I'm doing it will always work.

I hope to have something publishable in a day or two.  It shouldn't be long.

Steve

• ###### 11. Re: overlapping data points

I think Steve is working on an alternate method and a post. I simply applied Method 2 from this post, but using two sets of random number fields and two different seed values (the second one is just the first seed value divided by 2). Compute both of them using the Response field and it looks like this.

• ###### 12. Re: overlapping data points

Katie,

Here's a different approach that doesn't require random number generation.  You can apply it to your example immediately,  The only down side is that you cannot produce a trend line.

1. Change the rows measure to discrete (right-click and choose discrete)
2. Change the columns measure to discrete.
3. Change the mark type to circle.
4. place CNT(RespondeID) on the size button.

You will get something that looks like this:

• ###### 13. Re: overlapping data points

Hi Steve,

Here's something I did back in March that generates a compact view of non-overlapping points; however like your jittered boxes it's not going to get absolutely accurate trend lines because the measure used for display is not the real measure. I did this for some sales data, but it would work with survey data.

The marks are essentially an NxN trellis chart, where N is the (rounded up) square root of the number of marks so we'll have something that looks like a box. In this case, I didn't try to center the box on each original x/y coordinate, I found that too confusing to locate when there was a small number of points, so the start of each box is the mark in the upper left.  Here's a link to the original post Re: Re: Highlight top customer by day and the workbook is attached.

Jonathan

• ###### 14. Re: overlapping data points

Jonathan,

Indeed, the trend line would be an approximation and not quite accurate.  I chatted with Joe about this and he was able to build the trend line using the actual values with a table calc.  You don't get the trend model info this way, but by placing the right stuff on the level of detail you do produce a tooltip that gives you the y=mx + b values.

I doubt I'll ever use the faux trend line, but wanted to make sure it could be built.

I've got everything working now including parameter-based "compare this with that" and a parameter to control the width of the jitter.  I just need to write the actual post.

Stee

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