version 10.0
capture log close

*---------------------------------------------------
* the above command closes a log file that has
* inadvertently been left open. Trying to open a new
* log file when one is already open causes an error.
*---------------------------------------------------
log using chap02, replace
use food, clear

*------------------------------------------------
* Be careful when using above command that you do
* want to clear Stata's memory.
*------------------------------------------------

* examine data
describe
browse
list
list in 1/2
list in 11/20

* compute summary statistics
summarize

* summarize food expenditure with detail
summarize food_exp, detail

* simple plot data
twoway (scatter food_exp income)
more

*------------------------------------------------
* The more command pauses output so graph can be
* examined.
*------------------------------------------------

* enhanced plot
twoway (scatter food_exp income), ylabel(0(100)600) xlabel(0(5)35) title(Food Expenditure Data)
more

* compute least squares regression
regress food_exp income

* compute elasticity at means
mfx compute, eyex at(mean)

* calculate fitted values & residuals
predict yhat, xb
predict ehat, residuals
browse

* plot fitted values and data scatter
twoway (scatter food_exp income) (lfit food_exp income), ylabel(0(100)600) xlabel(0(5)35) title(Fitted Regression Line)
more

* examine variances and covariances
estat vce

* add observation to data file
edit
set obs 41
replace income=20 in 41

* obtain prediction
predict yhat0
list income yhat0 in 41

* save data
save chap02.dta, replace

* close log
log close

* translate smcl to text file
translate chap02.smcl chap02.txt, replace