# Displaying weighted counts through symbology

I have an Excel table of observational data.

``````Loc         Latitude    Longitude       Date       Survey?    Observed?
YDL         42.20833333 -83.62344444    8/15/16    NO         YES
YDL         42.20833333 -83.62344444    8/16/16    NO         YES
YDL         42.20833333 -83.62344444    8/17/16    YES        YES
YDL         42.20833333 -83.62344444    8/18/16    YES        NO
Courthouse  42.24027778 -83.61861111    8/15/16    YES        NO
Courthouse  42.24027778 -83.61861111    8/16/16    YES        YES
Courthouse  42.24027778 -83.61861111    8/17/16    YES        NO
Courthouse  42.24027778 -83.61861111    8/18/16    YES        YES
EMU         42.24027778 -83.61861111    8/15/16    NO         NO
EMU         42.24027778 -83.61861111    8/16/16    NO         NO
EMU         42.24027778 -83.61861111    8/17/16    NO         NO
EMU         42.24027778 -83.61861111    8/18/16    YES        YES
``````

I have converted this to a feature class and added it to a map:

I want these points to be proportional symbols, based on the count of 'Yes' values in the 'Observed' column. For example, YDL has 3 YES values, so it should be larger than EMU (2 YES) and EMU (1 YES). I managed to do this by basing the symbology off the Observed column, and changing the symbols based on the 'Count' column in the symbology tab of each category:

Here's the catch. I want to somehow weight those counts against the number of values in the SURVEY column, because we surveyed some locations more frequently than others. For instance, we only surveyed once at EMU, but we surveyed 4 times at Courthouse, which gives a higher probability of observing something at the Courthouse.

Can I do this in ArcMap? It would be nice to not have to restructure my data, but maybe it would be easier if I just had one row for each point, and a separate column to create a weighted count as described above?

• You will need to create an additional column to calculate this value into. – jbalk Oct 24 '16 at 2:22
• Can you be more specific? Are you saying I should take the approach I described in my question (one row per point, with a new column for the new value)? Or are you talking about something else? – ale19 Oct 24 '16 at 13:47
• I'm saying you need a new field to hold the weighted values. If you can calculate those values without creating individual points, do that. If not, create additional points. – jbalk Oct 24 '16 at 23:24