How can I display overlapping data points on a scatterplot?

How can I display overlapping data points on a scatterplot?

Post by am.. » Fri, 20 Jun 2003 20:27:00



How can I display overlapping data points on a scatterplot?

   I have a problem displaying my SPSS data. I have got about 250
values in 2 catagories (=sample size), which I want to display in a
single graph (scatterplot?). The vast majority of the values in both
catagories are 0. Only 15% in catagory 1 are elevated (range 0-40) and
20% in catagory 2 (range 0-50).
My problem is that my data points (not elevated)are graphed on top of
each other, and you cannot tell from the scatterplot how many data
points each symbol on the graph represents, not even roughly.

I tried jittering and using the "sunflowers" option in SPSS.

The sunflower option did not help, because the amount of normal values
is too big to be clearly displayed. Jittering did not help neither,
because the SPSS-graph program is jittering only vertically and not
horizontally.

Maybe anybody has an idea how to display my data.
Any idea which graph data exploration program I may use?

Thanks for the help

Daniel Berg

 
 
 

How can I display overlapping data points on a scatterplot?

Post by Brendan Halpi » Fri, 20 Jun 2003 21:12:53



> How can I display overlapping data points on a scatterplot?

>    I have a problem displaying my SPSS data. I have got about 250
> values in 2 catagories (=sample size), which I want to display in a
> single graph (scatterplot?). The vast majority of the values in both
> catagories are 0. Only 15% in catagory 1 are elevated (range 0-40) and
> 20% in catagory 2 (range 0-50).
> My problem is that my data points (not elevated)are graphed on top of
> each other, and you cannot tell from the scatterplot how many data
> points each symbol on the graph represents, not even roughly.

1: A scatterplot is *probably* the wrong device, but ...

2: ... if you're convinced it's what you want, do the "jittering"
yourself:

compute VARjit = VAR - 0.2 + uniform(0.4).

To return to point 1, a set of histograms (one per category) or a
box-plot might do what you want more effectively.

Brendan
--
Brendan Halpin,  Department of Sociology,  University of Limerick,  Ireland
Tel: w +353-61-213147 f +353-61-202569 h +353-61-390476; Room F2-025 x 3147


 
 
 

How can I display overlapping data points on a scatterplot?

Post by Arthur J. Kendal » Fri, 20 Jun 2003 21:59:20


See if this brings you closer to what you are looking for.

* see how many cases are at (0,0).
temporary.
recode x, y (0=1) (1 thru h=1) into dichot_x and dichot_y.
crosstabs tables = dichot_x by dichot_y.

* scattergram the remaining cases.
select if (x gt 0 or y gt 0).
Igraph . . .

Hope this helps.

Art

Social Research Consultants
University Park, MD USA
(301) 864-5570


> How can I display overlapping data points on a scatterplot?

>    I have a problem displaying my SPSS data. I have got about 250
> values in 2 catagories (=sample size), which I want to display in a
> single graph (scatterplot?). The vast majority of the values in both
> catagories are 0. Only 15% in catagory 1 are elevated (range 0-40) and
> 20% in catagory 2 (range 0-50).
> My problem is that my data points (not elevated)are graphed on top of
> each other, and you cannot tell from the scatterplot how many data
> points each symbol on the graph represents, not even roughly.

> I tried jittering and using the "sunflowers" option in SPSS.

> The sunflower option did not help, because the amount of normal values
> is too big to be clearly displayed. Jittering did not help neither,
> because the SPSS-graph program is jittering only vertically and not
> horizontally.

> Maybe anybody has an idea how to display my data.
> Any idea which graph data exploration program I may use?

> Thanks for the help

> Daniel Berg

 
 
 

1. The data points in the Scatterplot dissapear...Why?

I am running both the SPSS 8.0 and SPSS 11.0. I made 24 interactive
scatterplots. They are gathered in 6 groups inside the output file. I close
the file. Save it to a diskette. Take the .spo file and open it in another
computer. And the data points in the last 3 or 4 scatterplots of each one of
the 6 groups dissapear. I thought it was the diskette. But i opened the file
in the original file and the data pints dissapeared too! What may be wrong?
I attached the file.
Thanks SPSS Gurus for helping on this matter..

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