Table:
outcome variable
regression results

coefficient
standard error

log of wages
-0.036
0.020

employed full time
-0.083
0.023

employed in permanent job
-0.003
0.023

covered by collective bargaining agreement
-0.551
0.015

union membership
-0.605
0.018

Examine the table in this image and extract any merged cell regions. Please format the merged cell regions as JSON {'top-left':(R1, C1), 'bottom-right':(R2, C2)}, with (R1, C1) indicating the (row_id, column_id) of the top-left cell and (R2, C2) the bottom-right cell in the merged regions. Remember that the R1, C1, R2, C2 all start from 1.

The merged cell regions are as follows:
{'top-left':(1, 1), 'bottom-right':(2, 1)}
{'top-left':(1, 2), 'bottom-right':(1, 3)}.