The degree of unbalance in published large phylogenies cannot be explained by weak systematic treatment because our results indicate a nonrandom
selection of trees by systematists.
A purposive, nonrandom
sampling of participants was used, and data were collected through a survey of 50 students, 25 staff members, and 3 administrators.
National Laboratory show how it is possible in theory to reduce an entire system's error rate to acceptable levels, even when the faults arise from nonrandom
interactions between quantum bits.
For the last two decades the experimental evidence on associations of alleles at different allozyme polymorphisms has shown that nonrandom
associations (gametic disequilibria) are rarely detected in natural populations of outcrossing species (Langley, 1977; Hedrick et al.
Highlighted are problems associated with the use of listservs, e-mail addresses, formats for downloading and compiling data, and the nonrandom
nature of the resulting sample.
Half the adoptive families originally contacted for the survey declined to participate, yielding a nonrandom
sample; a nonadopted control group given the same survey was not included; and researchers failed to establish how much security teenagers derived from their reported sense of emotional attachment to adoptive parents.
Conventional estimates of class-size effects are shown to be severely biased by the nonrandom
placement of students between and within schools.
Flaws included small, nonrandom
samples, lack of control groups or comparisons with other chronic medical conditions, and absence of reliable psychiatric diagnoses.
sample was selected by partnership staff.
But this study was clearly nonrandom
, since it involved only homes where the residents were worried enough to pay for radon measurements.
In majority of cases of B-cell ALL there is an abnormal karyotype which is seen in the form of nonrandom
numerical or structural changes that can be detected by cytogenetic analyses.
The significantly nonrandom
(southerly) orientation of egg cases, previously unreported but observed in all 3 y, is an unexpected result and prompted our hatching study and the later ibutton/temperature study.