Jack Welch and some of the cable news programs are casting aspersions on the legitimacy of the Labor Department's latest jobs numbers, asserting that the unexpectedly large drop in the unemployment rate indicates that someone cooked the books to help President Obama right before the election.
After all, the household survey - the survey that the unemployment rate comes from - showed that the number of people with jobs rose 873,000 in September, when the gain had averaged 164,000 each month earlier this year.
Here's the thing. These numbers are always tremendously volatile, but the reasons are statistical, not political. The volatility arises because the numbers are based on a tiny survey with a margin of error of 400,000. Every month there are wild swings that no one takes at face value. But the swings usually attract less attention because the political stakes are lower.
The numbers, by the way, are especia lly imprecise (and prone to revision) when the economy is making a turn, or when regular seasonal patterns start to change - which may have been happening in September with the college school calendar and summer jobs.
One of the biggest sources of volatility in the last couple of months (and one of the major contributors to the big bump in job-getters in September) was the group between the ages of 20 and 24.
Historically, the employment levels for that group have dropped sharply in September, probably because many people in their early 20s are leaving summer jobs and going back to school.
For each year since 1948, the average level of employment for this group has fallen by 398,000 from August to September. In fact, before this year, employment for this age group had risen just two times in that period: 1954 (a gain of 5,000), and 1961 (a gain of 22,000).
This year was the third time on record that the number of people in this age group gained jobs in September, and the gain was big: 101,000.
How to explain this major deviation from the historical trend, other than conspiracy theories for which there is no evidence?
If you look back at August, an unusually high share of this age group stopped working, compared to past employment patterns in August. From 1948 to 2011, the number of those 20 to 24 who had jobs fell by an average of 98,000 from July to August. This past August, it fell by 530,000, the biggest loss on record.
Over the last couple of decades, the job losses for this age group have been getting bigger each August, suggesting that over time young people have been leaving their summer jobs earlier and earlier.
In other words, what we might be seeing is an evolution of seasonal patterns - people starting school and leaving their summer gigs earlier in the summer - which has big implications for how the Labor Department digests and reports the monthly jobs d ata.
The Bureau of Labor Statistics adjusts its raw survey data to correct for seasonal patterns, and since we've come to expect a decline in employment for those 20 to 24, the economists at the bureau increased the level of employment for this group in the seasonally adjusted numbers.
Changes in seasonal patterns like this one can introduce more error into the headline numbers, and can at least partly explain why the overall change in household employment looked so much bigger in September than seems plausible. After seasonal adjustment, the increase in employment among those 20 to 24 was given as 368,000. That's about 42 percent of the overall increase in employment growth for people of all ages. (After making seasonal adjustments, the employment level for 20- to 24-year-olds was reported as declining by 250,000 in August.)
All of which is to say the bureau aims to release the most informative numbers it can. But it is seeking to measure the state of the American job market quickly, based on surveys that are inherently incomplete - and the adjustments that are meant to fill in the gaps have their own shortcomings, particularly when seasonal trends change.
In case you still believe that the models the bureau uses are being manipulated to put President Obama in a better light, note that there are not even any political appointees currently serving in the Bureau of Labor Statistics. They're all career civil servants who have worked under both Republican and Democratic administrations. (The commissioner of the bureau is supposed to be a political appointee, but right now that position is vacant. The acting commissioner, Jack Galvin, has been temporarily holding the position since January, and he is a career civil servant.)
I also called the Bureau of Labor Statistics to ask about another conspiracy theory I heard: that the bureau changed one question on its household survey recently. Fran Horvath, a senior economist, said that was not so.
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