I’m trying to run a t-test using a survey design object with the survey package. When the variable of interest is a subset of two groups in an ordered factor variable, I get an error message:

“error in evaluating the argument ‘x’ in selecting a method for function ‘format’: group must be binary”

If I convert the variable to a non-ordered factor variable, the svyttest() function works fine. Is there a way to use svyttest() with an ordered factor variable?

I expected the svyttest() result to be the same whether my variable was ordered=T or ordered=F. It only works if ordered=F.

svyttest(obesityAdultCalc~education1, subset(adult_obesity_2123_design (education1=="low"|education1=="high")))

education1 = case_when(level==1 ~ 'low', level==2 ~ 'medium', level==3 ~ 'high', TRUE ~ NA_character_) %>% factor(.,levels=c('low','medium','high'), ordered=T)

education1 = case_when(level==1 ~ 'low', level==2 ~ 'medium', level==3 ~ 'high', TRUE ~ NA_character_) %>% factor(.,levels=c('low','medium','high'), ordered=F)