okay hello, i am in need of help trying to learn how to use stata for econometrics! I do not know how to generate or find the u^2 or the (uhat)^2

i am trying to find the var of error (sleep) dependent only on gender

So i did predict yhat and want to regress uhat^2 dependent on male

this is the example our professor used to explain for stata

"1. Estimate the model of interest

realearnings= 𝛽 +𝛽𝑎𝑔𝑒+𝛽𝑎𝑔𝑒2+𝛽𝑒𝑑𝑢𝑐𝑎𝑡𝑖𝑜𝑛+𝛽h𝑜𝑢𝑟𝑠𝑤𝑜𝑟𝑘𝑒𝑑+𝑢

ln(𝑢̂2) = 𝛿0 + 𝛿1𝑎𝑔𝑒 + 𝛿2𝑎𝑔𝑒2 + 𝛿3𝑒𝑑𝑢𝑐𝑎𝑡𝑖𝑜𝑛 + 𝛿4h𝑜𝑢𝑟𝑠 𝑤𝑜𝑟𝑘𝑒𝑑 + 𝑣""

But i dont know how to calcluate u!!!

HELP P

i am trying to find the var of error (sleep) dependent only on gender

So i did predict yhat and want to regress uhat^2 dependent on male

this is the example our professor used to explain for stata

"1. Estimate the model of interest

realearnings= 𝛽 +𝛽𝑎𝑔𝑒+𝛽𝑎𝑔𝑒2+𝛽𝑒𝑑𝑢𝑐𝑎𝑡𝑖𝑜𝑛+𝛽h𝑜𝑢𝑟𝑠𝑤𝑜𝑟𝑘𝑒𝑑+𝑢

- Calculate ln(𝑢̂2)
- Estimate the secondary regression

ln(𝑢̂2) = 𝛿0 + 𝛿1𝑎𝑔𝑒 + 𝛿2𝑎𝑔𝑒2 + 𝛿3𝑒𝑑𝑢𝑐𝑎𝑡𝑖𝑜𝑛 + 𝛿4h𝑜𝑢𝑟𝑠 𝑤𝑜𝑟𝑘𝑒𝑑 + 𝑣""

But i dont know how to calcluate u!!!

HELP P

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