One often compiles the allowed beta decay in terms of a logft which stands for log$_{10}$ of the $ft_{1/2}$ value.

The values of the coupling constants for Fermi decay, $g_{V}$, and Gamow-Teller decay, $g_{A}$ are obtained as follows. For a $0^{+} \rightarrow 0^{+}$ nuclear transition $B(GT)=0$, and for a transition between $T=1$ analogue states with $B(F)=2$ we find $$C = 2 t_{1/2} f.$$ The partial half-lives and $Q$ values for several $0^{+} \rightarrow 0^{+}$ analogue transitions have been measured to an accuracy of about one part in 10000. With phase space factors one obtains $$C = 6170(4)$$ This result, together with the value of $K_{o}$ can be used to obtain $g_{V}$.