where N is the sample size, X is the sample mean, ? is the standard
deviation, and the subscripts a and b denote each group. When the
black-white difference for a specific test is reported subsequently
in the text, this equation has been used to compute it.
34 The Long Term Trend Study with consistent data for the NAEP from
the early 1970's through 2004 is now available in mathematics and
reading for students tested at ages nine, thirteen, and seventeen.
35 For nine-year-olds, the gap in reading scores expressed as points
was smaller in 2004 (26 points) than in 1988 (29 points), but the
difference in standard deviations was fractionally larger (.76
standard deviations in 2004 as compared with .74 in 1988).
36 Hedges Atacand 8mg Tablets and Nowell (1998): 154.
37 I will venture a prediction that a variety of academic achievement
measures in elementary and secondary school will soon show renewed
convergence because of the No Child Left Behind Act, which puts
schools under intense pressure to teach to the test in basic skills.
If students are drilled on limited ranges of subject matter, scores
will tend to rise. The more basic the tests Atacand 16 Mg Price are (that is, the easier
they are), the more that improvements among the least skilled will
affect the mean. Also, the higher the stakes facing a school-and the
No Child Left Behind Act makes those stakes very high indeed-the
greater will be the incentives for administrators to use some of the
many resources at their disposal to make the results come out right,
through the judicious manipulation of suspensions and absences, and
through outright cheating (yes, it has been known to happen). Some
convergence in black and white test scores will probably occur, but
partitioning that effect among the competing explanations is a task
that will take a few years. Insofar as the convergence has been the
result of teaching to the test and of artifacts, it will be temporary.
38 In a given year, IQ Buy Atacand Hctz tests and academic tests administered to the
same sample will produce similar results. Thus, it is possible to
make a reasonably good guess about a person's IQ based on his SAT
score compared to the distribution of SAT scores in a given year, and
after taking the composition of the SAT population into account. But
the results of academic tests are sensitive to changes in academic
achievement, whereas IQ tests are explicitly designed to measure a
general mental factor, g, that is independent of academic
achievement. A notorious illustration of the way that academic test
scores can drop is the period during the 1960's and 1970's when SAT
scores declined substantially, even after accounting for changes in
the pool of test-takers (Murray and Herrnstein 1992). The
intelligence of American youth was not declining, just their academic
39 The significance of g-loadings is discussed later in the text. In
terms of interpreting trends over time, the problem is that tests are
not equally good measures of g. They go from poor (e.g., a basic
reading test) to excellent (the Atacand 60 Mg most highly g-loaded, individually
administered IQ test). It is as if you were trying to measure changes
in average height with measuring tapes of varying accuracy. For a
statement of the no-change position, see Gottfredson (2005a), or a
summary of her argument in Gottfredson (2005b).
40 The .97 figure comes from my analysis of the proxy AFQT score in
the most recent release of the 1997 cohort of the National
Longitudinal Study of Youth (NLSY). I call it a proxy score because,
eight years after the test battery was administered, the Armed Forces
still has not gotten around to creating an official AFQT score. The
version created by the NLSY staff is a composite of the same subtests
used for previous versions of the AFQT, and takes the subject's age
into account. The NLSY has released the percentile scores, which I
converted to standard scores. The analysis used the NLSY's sample
weights to make the results representative of the national
population. The NLSY data can be downloaded online.
41 I take the 1.10 figure from Roth, Bevier, Bobko et al. (2001), a
meta-analysis of the black-white difference in both achievement tests
and IQ tests. The Roth et al. results are necessarily reflective of
pencil-and-paper tests, because that is where the overwhelming