As a follow-up to the post looking at scholastic improvement by state as measured by the NAEP, the same follows, for whites exclusively. Improvement is measured by looking at how the 2003 4th grade cohort compares to the 2007 8th grade cohort in each individual state. The better the latter performs relative to the former, the greater the improvement:
Unfortunately, the NAEP site does not give an average 2007 score for whites in the District of Columbia, for lack of sample size. Algebraically figuring the white score based on its proportional representation puts DC at (.21), between Rhode Island and Virginia.
The actual number could vary widely from that estimate. If, instead of 3% (the NAEP only gives these percentages in whole numbers), only 2.5% of 8th graders in DC's public school system are white, it is easily propelled into the top spot. Whatever the case, DC's whites represent a tiny contingent--there are less than 3,500 whites in the entire district, K-12.
While the white variance by state seems, in sum, wider than is the case for states when all races are considered, that's a consequence of how the data are presented. The standard deviations in each case are derived from the totality of scores for all races, and for whites only, respectively. Because race figures significantly in determining absolute scores, including all races creates more overall variability, and hence in terms of actual scores, 'larger' standard deviations (by about 50%) than is the case when only whites are considered.
Steve and other commenters raise questions about the influence of a brain drain phenomenon (DC attracting upper-echelon immigrants and pushing out impoverished blacks, Hispanics moving to the South and especially North Carolina, the upwardly mobile leaving the backcountry culture of West Virginia, and I also wonder what the consequences are for states that have taken in a substantial number of New Orleans' refugees, etc).
Around three percent of the population moves its primary residence into a new state each year. But over a four year span, the cumulative effect might be substantial. To the extent that this explains the improvement (or deterioration), it takes away from the measure's utility as a proxy for teaching effectiveness by state.
An influx or outflow will also presumably have some effect on the students who have stayed put. However, Nevada's whites have done well in the face of one of the greatest foreign migration rates in the country. On the other hand, California's whites, who experience an even higher rate of foreign migration into their state as their neighbors to the east do, haven't fared as happily.
Although North Carolina shows a lot of deterioration when both all races or just whites are looked at, it's conceivable that in the Old North state along with the rest of the country, migration patterns are changing the classroom atmosphere for the students who remain, for better or worse.
Of course, immigrants from outside the US are not the only migration force at the state level, as most of the people who plant themselves somewhere new have come from another American state.
Also, the proportion of kids in private schools varies by state. Children who split their pre-collegiate schooling between the private and public spheres tend to start in the former and end in the latter (adjusted for total population in primary and secondary schools across the US, kids in their primary years are about 30% more likely to be enrolled in private school than those in their secondary years are). Since, on average, kids in private schools tend to be a notch above those in public schools, a higher rate of children in private schools should be beneficial in terms of improvement.
Louisiana has the highest percentage of children enrolled in private schools in the country, and it does poorly. But New Hampshire, with the second smallest percentage of private school kids doesn't do well, either.
I do not mean to equivocate on the demographic angles, so as to make the method appear a viable way of approximating the general effectiveness of public pedagogical strategies. I will look at all of these factors (and any other potentially viable suggestions) in light of improvement by state.