RSSI or DB information

I want to see Received signal strength at Xbee module at different distance.
I am using ATDB command on X-CTU to check received signal strength, my question is how accurate are these values.
Because in 2 meter indoor place I am receiving DB hex value is ranging from 32 to 47 .
I believe this range is wrong as both modules are very near to each other and values are differing more than 30decimal values.

1)Can anyone suggest me how can I get accurate values and what is the best way to compare signal strength respect to distance.
Does these values differ indoor and outdoor very much or are almost same