Subject: Do the accuracy of astronomical observations increase as a function of time

I was researching a paper "Test of General Relativity from 3 dimensional orbital 
geometry of a binary pulsar" by VanStraten , Bailes et al.They have mentioned 
that they expect the precision of a value to increase as a function of 
t^3/2(t=time).I dont understand how a given observation's accuracy can improve 
as a factor of time in mathematical terms. Are there systems whose accuracy can 
be expressed as a function of time??

Re: Do the accuracy of astronomical observations increase as a function of time