Is an obscure detail about how the Labor Department tabulates workers’ hours obscuring an “Obamacare”-driven shift toward part-time work?

No.

One of the most common arguments against President Barack Obama’s signature health law is that it will drive employers to shift from full-time to part-time workers. That’s because the law requires most midsize and larger employers to provide health insurance to employees who work at least 30 hours per week. Some companies say they’re already cutting workers’ hours.

As we pointed out last week, there’s little evidence of a broad-based shift, at least so far. Most significantly, there’s been no meaningful increase in the share of workers saying they usually work less than 30 hours at their primary jobs.

But some observers have noted that in its data, the Labor Department rounds workers’ hours up to the next whole number. That means someone who works 29.5 hours would be reported as working 30 hours. So if companies are cutting workers’ hours back to just under the 30-hour cutoff — as some report doing — it might not be reflected in government statistics.