In this context, a possibly more severe form of bias could be introduced by loss to follow-up, especially if it differs between exposed and unexposed subjects [ 73].
In 2005, a new kind of hierarchical clustering method was introduced by Palla et al. that differs in two ways from Ward's method: it can be used on data on which no full similarity matrix is defined and it can produce overlapping clusters, i.e., allow for multiple membership of items in clusters.
Classifications of CAM modalities have differed but a generally accepted schema was introduced by the NCCAM [ 12] and is in common use.
While this suggests that minimal bias was introduced by differential follow-up, the possibility still exists that children lost to follow up differ on unmeasured variables.
Salazar begged to differ: the draft bill brought before Congress last year, she said, had been introduced by a Democrat from Harlem, and was aimed at white people.
Kathryn Bigelow was introduced by Norman Jewison.
They were introduced by mutual friends.
This idea was introduced by Frege.
Carson was introduced by David Muir and Martha Raddatz.
The distinction was introduced by Bales (1971).
