"have no variation" is a correct and usable phrase in written English.
For example, you could say "The rules of the game have no variation - everyone must follow the same rules."
After municipalities that have no variation in the outcome are excluded (which is necessary due to the municipality level fixed effects which would otherwise perfectly predict the outcome), the sample consists of 27,445 pregnancies.
The return rate was 62%, and it is possible that that the non-responders have no variation in practice.
Pigs and bison species have no variation within GHR exon 10, but show high haplotype diversity for the PRLR exon 10.
Despite the high degree of variability in DRB1-e2 we could, to our surprise, find 19 stretches of a length 3 13 bp that have no variation at all among different DRB1-e2 (Table 3 and Fig. 6).
Interspersed among the highly polymorphic areas of DRB1-e2, we found multiple short stretches of bases that have no variation at all between the DRB1 alleles in the dataset.
Septic shock requiring MV (13 % of cases) had no variation in mortality across the lower groups of day 1 fluid use (1 L to 5 L).
The pure tones had no variation in pitch (Praat reported a mean SD<1/100000 of a semitone, averaged across the 24 test tones), whereas the piano (mean SD<1/100 of a semitone) and synthesized vocal (mean SD<1/20 of a semitone) tones had minor variations.
We split these pedigrees into nuclear families for analysis, discarding subpedigrees which had no variation in observed phenotype or marker alleles or fewer than 2 individuals with observed genotypes, and discarding individuals without offspring which had neither observed phenotype nor genotype.
In contrast, Npm1 has no variation that is private to NZO/HlLtJ, so we eliminated it as a candidate gene.
As expected, many of the genes in windows under strong purifying selection had no variation and thus calculating Tajima's D was not possible.
