It remains possible that there are unobserved characteristics omitted from the model that could generate biased estimates.
The second issue is that inferences from listwise-deletion estimation can be biased if the observed data differs systematically from the unobserved data.
Additionally, findings may be confounded by unobserved influences and, as with any model, results can only be suggestive.
There are reasons to believe that unobserved information such as forest quality can significantly correlate with unobserved variation in the collection function.
One somewhat surprising aspect is the virtual omission of any discussion of confounders, especially unobserved confounders.
Ignoring the mixture distribution of the unobserved genotype, they were able to estimate and test the disease penetrance difference between alternative genotypes.
The correlation between the two equations reflects unobserved factors, which affect both admission decisions and survival.
Since the values of observed variables are known with certainty, only unobserved variables are the object of scrutiny in abductive methods.
