The phrase "are two strata of" is correct and usable in written English.
It can be used when discussing different layers or levels within a particular context, such as social, geological, or conceptual frameworks.
Example: "In the study of society, there are two strata of class that significantly influence economic mobility."
Alternatives: "are two layers of" or "consist of two levels of".
"There are three strata of prostitutes.
The sample was stratified by phases of the campaign, such that there were three strata, each representing one phase of the communications and net distribution campaign.
Within this market, there are three different strata of technologies, known as "stacks".The first stack is called "advanced metering infrastructure", or AMI.
Below right of the term 'language system' are the four strata of language: semantics, lexicogrammar, phonology and phonetics.
If the distribution of C in controls is identical to the distribution of C in cases, the control-to-case ratio will be identical in the two strata of C. Of course, it will also be identical to the control-to-case ratio in the entire sample (k1 = k2 = 4).
The purpose of the oscillatory diving behavior may be to move between two strata of water to track chemical cues [32] or perhaps utilize visual cues which are enhanced when looking up against down-welling light [39].
The HRs for age at menarche, height and BMI were homogenous across the two strata of parity, whereas the trend of increasing risk with increasing age at menopause was more pronounced among parous women.
To prevent bias, stratified sampling procedure was employed to create two strata of the population based on gender.
The same procedure was then conducted for two strata of children separated by breastfeeding duration.
The effect of serum 25(OH) vitamin D on chronic liver disease mortality was similar across these two strata of serum calcium (OR for Q4 vs Q1: 0.28 and 0.43, respectively).
