I am trying to determine overlap percentage of two polygon layers in QGIS. One layer is Census Block Groups and the other is from local government units. Sometimes the two layers are perfect fits, but more often both the Census Blocks and the other layer will have to be grouped together to find the best fit. Here is a picture of the layers for reference: enter image description here

I am trying to use the Overlap Analysis tool but can't get it to work. I am not able to select the second layer and if I click run I receive the following error -

Wrong or missing parameter value: Overlay layers

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I have found a few other post where people have a similar error with QGIS but the solutions dealt with plugins I do not have installed. I have tried to use the Join Attribute by Location layer but the output includes polygons that touch and I for the life of me can't find the right settings to make it work. I believe the Overlap Analysis is likely the right tool to use. I have also tried to change the input layer to many other shapefiles and all of them produce the same issues or the error and the 2nd layer being greyed out.

EDIT: The answer fixed my problem. I also found this post which was so helpful and explains how to intersect Census to Precinct shapefiles: Dividing polygon and assigning values ​proportionally (population) using QGIS?

1 Answer 1


You must click the ... button to the right

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Then tick the box beside the layer(s) of interest and click ok

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