He claims that researchers need to pay more attention to geographic and temporal units used in research and need to understand the causes and consequences of nonrandom selection
After controlling for potential nonrandom selection
, the coefficient on the HSCT variable measures the treatment effect, that is, the difference in the probability of death that exists between HSCT recipients and those who underwent alternative treatments.
Unfortunately, the potential bias created by nonrandom selection
into employment is even more severe for fathers than mothers -- most nonworking men are involuntarily unemployed and probably do not devote much of the extra nonmarket time to investments in children.
First, they provide upper- and lower-bound estimates of the impact of CSRP on students' academic achievement, taking into account their subsequent nonrandom selection
into higher versus lower quality school settings.
GAO's analysis, including a review of a nonrandom selection
of contracts, indicates that the U.
Here is the answer: Subsequent to these random events, the system (antibody-secreting cell, or entire organism) is put through a very nonrandom selection
For example, if parents who really value education were more likely to pull their children out of a cohort with a particularly high proportion of peers from troubled families, such nonrandom selection
would cause us to erroneously attribute lower performance to the presence of the troubled peers.
The limitations of this descriptive study were numerous, including the small number of RA students participating in the study, the nonrandom selection
of clinical facilities, the limited time period during which the data were collected, the nonrandom selection
of procedures and patient management activities and the widely generalized estimations of procedure times, procedure reimbursements, interpretation reimbursements and hypothetical R.
This variation is then subjected to nonrandom selection
First, previous research failed to account for the possible nonrandom selection
of home- and community-based services in evaluating the impact of the waiver on costs.
At first glance one might guess that this apparent relationship is induced by nonrandom selection
(only if a giver gives a non-cash gift is it included in the yield calculation).
On the other hand, models of nonrandom selection
predict an "illusory" union earnings premium, or a differential driven by unobserved differences between union and nonunion workers in skills and preferences.