Archives for the Month of November, 2008

Benchmarking

In my previous post I cautioned against looping across observations, then showed how to do it anyway, using the example of reshaping a list from long to wide. A reader suggested, not unreasonably, that one might want to use reshape for that. He then proceeded with a code example, under the reservation that he did [...]

Looping across observations

People who stress that you very seldom have to do this in Stata are right. That's why I always forget how it's done. So here, for my reference and yours:
Today I looked at a table in .rtf format. It had test scores for a bunch of students in Poli Sci at the University of Cluj, [...]

Arguments

In an older post I wrote about the program capability in Stata. One thing I didn't say and I find increasingly useful these days is that you can pass arguments to programs.
Packaging a set of commands inside a program, to be read once and then invoked as many times as they are needed, is nice [...]

Data from MS Access to Stata

In my oldest post about the odbc load command I mentioned that you can pretty easily read data from MS Access into Stata, and even execute SQL commands from within Stata, but I dismissed the whole thing a bit too lightly. A recent look on Google Analytics showed that some people came here looking for [...]

Looking at your data: table vs. tabulate

Last night I got an e-mail from a reader, asking how to keep Stata from clipping long string values in two-way tables. This is his code:

clear
set obs 10

gen a = ""
replace a = "a123456789b123456789c123456789" if _n<5
replace a = "987654321x987654321y987654321z" if _n>=5
gen b = "value " + string(int(_n/4))

tab a b
tab a
You can see that the a [...]

Data from Excel to Stata, take two

I don't like spreadsheets. I like data sets and matrices. But I get data in Excel workbooks all the time, and it's a pain in the neck. This will never go away altogether, but if my Stata-using colleagues could be persuaded to quit sending me spreadsheets, that would at least cut down on the volume. [...]

Leading zeroes

I am working on a project where occasionally I need to keep time using dates in the format YYYYMMDD. I sometimes also need to move back and forth between these dates and numeric year, month, day, which requires things like turning the numeric month 1 into the string "01".
The general syntax for turning numbers to [...]

Old-school summary statistics

If you do this
sysuse auto
sum price, detail
return list

you will see that Stata saves summary statistics in a few scalars with some rather apt names, like r(N) for count, r(mean) for mean, or r(p99) for the 99th percentile.
Those names used to be far less descriptive until a few years back. If you come across code written [...]