can you include a loop inside a model?
Posted: Mon Jul 26, 2010 1:05 pm
Hi,
I'm wondering if it is possible to include a loop inside a model. My model consists of single equations for GDP, inflation, the Fed funds rate, and the long-term interest rate. Here is the tricky part: the long-term interest rate in each quarter is a weighted sum of the short-term rate over the following 40 quarters. To calculate the long-term rate, I use the following loop:
genr z = 0
for !x = 0 to 39
genr zz = rtb(!x)*(0.98^!x)*(1 - 0.98)/(1 - 0.98^40)
genr z = z + zz
next
where (0.98^!x)*(1 - 0.98)/(1 - 0.98^40) are the weights. (I posted a question in the data manipulation section asking if there was a summation command that would do this so that I could avoid using a loop, but the answer is no.) The long-rate is an explanatory variable in the GDP equation, so it cannot simply be calculated after the model has solved.
Thanks for your help,
Matt
I'm wondering if it is possible to include a loop inside a model. My model consists of single equations for GDP, inflation, the Fed funds rate, and the long-term interest rate. Here is the tricky part: the long-term interest rate in each quarter is a weighted sum of the short-term rate over the following 40 quarters. To calculate the long-term rate, I use the following loop:
genr z = 0
for !x = 0 to 39
genr zz = rtb(!x)*(0.98^!x)*(1 - 0.98)/(1 - 0.98^40)
genr z = z + zz
next
where (0.98^!x)*(1 - 0.98)/(1 - 0.98^40) are the weights. (I posted a question in the data manipulation section asking if there was a summation command that would do this so that I could avoid using a loop, but the answer is no.) The long-rate is an explanatory variable in the GDP equation, so it cannot simply be calculated after the model has solved.
Thanks for your help,
Matt