The Easter cards also revealed many of the same categories as well as the same
dichotomization. Of the 17 content categories, 76% had only one sex represented.
It "suggests a systematic and highly political
dichotomization in news coverage based on serviceability to important domestic interests."
Dichotomization is used to refer both to choices of story and to volume and quality of coverage: "choices for publicity and suppression" are "comprehensible in terms of system advantage," and "modes of handling favored and inconvenient materials (placement, tone, context, fullness of treatment) differ in ways that serve political ends." As they are careful to point out, theirs is not a model of totalitarian control, and it is not disproven by the fact that they themselves use the American media for much of their source material.
Theorists tend to simplify the world by
dichotomization, such as the West versus the non-West, and so on.
The variable advance was dichotomized for analysis by logistic regression using two rules, giving rise to two possible curricular situations: adjustment (adequate advance in the career for the selected
dichotomization criterion) and falling behind (curricular lag).
This threshold of
dichotomization was necessary because the options "[less than or equal to] 4 times" and "[greater than or equal to] 5 times" were the only ones shared by all three scale ranges.
Some writers feel that meta-analysis can correct for artifacts (e.g.,
dichotomization of continuous variables, imperfect construct validity, attrition), assuming that if the meta-analyst is sufficiently diligent in identifying and correcting for artifacts, all the variability in the true effect sizes will disappear (Hunter & Schmidt, 1990).
Specifically, I find his
dichotomization of the natural numbers into the symbolic, 'belonging to language and defined by the local culture', and 'the natural numbers defined by the mathematics or logic' unsustainable.
While this
dichotomization may elide nuances and exceptions to the rule--for example, the conducting of quantitative and administrative research in Germany--these perspectives do have implications.
As Cohen (1983) noted, assuming a bivariate normal distribution with correlation r, the "artificial"
dichotomization of one continuous variable at the mean reduces the variance accounted for to .64[r.sup.2]; if both are dichotomized at the mean, the amount of variance accounted for declines to .40[r.sup.2].
Factors identified as detrimental to statistical power in MMR hypothesis tests are related to (1) variable distributions (predictor variable range restriction, error variance heterogeneity), (2) operationalizations of criterion and predictor variable (measurement error, inappropriate metrics, artificial
dichotomization or polychotomization), (3) sample size (total sample size, sample size across moderator-based subgroups), and (4) predictor intercorrelation.(2) Next, each of these factors and their impact on the power of MMR are described.
A common problem, however, is that of false
dichotomization, wherein a continuous variable is erroneously treated as if it were a dichotomous variable.
Yet the
dichotomization of significant or not significant does just that.