  The Bose-Einstein correlation (BEC) in forward region ($2.0<\eta<4.8$)
measured at 7 TeV in the Large Hadron Collider (LHC) by the LHCb collaboration
is analyzed using two conventional formulas of different types named CF$_{\rm
I}$ and CF$_{\rm II}$. The first formula is well known and contains the degree
of coherence ($\lambda$) and the exchange function $E_{\rm BE}^2$ from the BE
statistics. The second formula is an extended formula (CF$_{\rm II}$) that
contains the second degree of coherence $\lambda_2$ and the second exchange
function $E_{\rm BE_2}^2$ in addition to CF$_{\rm I}$. To examine the physical
meaning of the parameters estimated by CF$_{\rm II}$, we analyze the LHCb BEC
data by using a stochastic approach of the three-negative binomial distribution
and the three-generalized Glauber-Lachs formula. Our results reveal that the
BEC at 7 TeV consisted of three activity intervals defined by the multiplicity
$n$ ([8, 18], [19, 35], and [36, 96]) can be well explained by CF$_{\rm II}$.
