I am producing some demographic tables, to include race, sex, and ethnicity. One of the tables is a crosstab of sex and race by ethnicity (Hispanic / not Hispanic). So far, there are no Hispanic participants in the study, but the table needs to be produced and sent to interested parties (i.e., regulatory agencies).
However, I have not been able to produce a table for the report. Obviously, the table would be all zeroes, but it is not being produced at all. It seems that this is a limitation of trying to calculate something that does not exist...
I have included example data below:
race.in <- read.table(
text = "race eth sex
b n f
b n f
b n f
w n f
w n m
w n m
a n m
a n m
a n f
ai n m
ai n f
ai n m", header = TRUE)
attach(race.in)
race.levels <- c("b", "w", "a", "ai", "nh")
eth.levels <- c("h", "n") # hispanic , not hispanic
sex.levels <- c("m", "f")
# this table is fine
table(factor(race, levels = race.levels), factor(sex, levels = sex.levels) )
# this table is fine
table(factor(eth, levels = eth.levels), factor(sex, levels = sex.levels) )
# table of race and ethnicity by sex
by(race.in, sex, FUN = function(X) table(factor(race, levels = race.levels), factor(eth, levels = eth.levels) ))
# produces NULL for table for levels of "h"
by(race.in, factor(eth, levels = eth.levels), FUN = function(X) table(factor(race, levels = race.levels), factor(sex, levels = sex.levels) ))
Is there any way to produce a table of zeroes? I know it's silly, but we have to report this, even though there is no data for this set of conditions...
I'm not clear why you don't just factor your variables in your data.frame. That makes creating tables much easier.
race.in$race <- factor(race.in$race, race.levels)
race.in$eth <- factor(race.in$eth, eth.levels)
race.in$sex <- factor(race.in$sex, sex.levels)
table(race.in)
table(race.in[c(1, 3, 2)])
# , , eth = h
#
# sex
# race m f
# b 0 0
# w 0 0
# a 0 0
# ai 0 0
# nh 0 0
#
# , , eth = n
#
# sex
# race m f
# b 0 3
# w 2 1
# a 2 1
# ai 2 1
# nh 0 0
You may also be interested in exploring the ftable function (for "flat" tables). For example:
> ftable(x=race.in, row.vars=1, col.vars=2:3)
eth h n
sex m f m f
race
b 0 0 0 3
w 0 0 2 1
a 0 0 2 1
ai 0 0 2 1
nh 0 0 0 0