Hello guys,
I am trying to replicate an approach from Barber, Brad M. and Huang, Xing and Odean, Terrance, Which Factors Matter to Investors? Evidence from Mutual Fund Flows (May 18, 2016).


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from the above equation what I understand we need to use nl command to execute equation 5. I am using following command for equation 5. The command is incomplete as I have not writing the control variables and all the 18 lags, that I will add later. Following is the command.

nl (flow = {b0} + {b1}*exp(-{lambda=1}*(1-1))*L1.alphaMAR + {b2}*exp(-{lambda=1}*(2-1))*L2.alphaMAR+{b3}*exp(-{lambda=1}*(3-1))*L3.alphaMAR +{b4}*exp(-{lambda=1}*(4-1))*L4.alphaMAR +{b5}*exp(-{lambda=1}*(5-1))*L5.alphaMAR +{b6}*exp(-{lambda=1}*(6-1))*L6.alphaMAR +{b7}*exp(-{lambda=1}*(7-1))*L7.alphaMAR +{b8}*exp(-{lambda=1}*(8-1))*L8.alphaMAR +{b9}*exp(-{lambda=1}*(9-1))*L9.alphaMAR) if obs>9

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Now I am not sure how to run equation 6. Following is an excerpt from the paper "We apply this decay function to the monthly alphas and factor-related returns for each fund-month observation. For example, when considering flows for funds in month t, we calculate the fund’s alpha as a weighted average of the prior eighteen monthly alphas:"



Thank you in advance for any help!