By Ray Charbonneau, Boston.com Correspondent

One of the things that makes the Boston Marathon unique is that it’s one of the few races in which runners have to earn their way in by running a fast time at another marathon. Unfortunately for some potential entrants, the recent boom in marathon running has meant that, even if they run a Boston Marathon qualifying time (a BQ), they still might not have a fast enough time to get in the race. To help alleviate this problem, the BAA has lowered the BQ times for 2013. Will the tougher standards be enough to ensure that everyone who qualifies can get in?

In 2011, thousands of runners, many of whom had worked hard for years to qualify, were unexpectedly blocked from running the Boston Marathon when the race filled up only eight hours after registration opened. In response, the BAA implemented a new “rolling admissions” registration process in 2012 to help ensure that the best runners could get into the race. When registration first opened, only runners who had run at least 20 minutes faster than their BQ time were allowed to register. A few days later, runners who were ten minutes under their BQ time were allowed in, followed by another round for runners five minutes under their BQ time. When registration was complete, some people were still shut out, but everyone who was at least 1 minute and 14 seconds under their BQ time successfully registered for the race.

The rolling admission process for the 2013 Boston Marathon started today. For 2013, the BAA lowered BQ times by five minutes across the board. In order to estimate the effect the new standards will have on the number of runners trying to register, I compared the number of qualifiers in 2011 (for Boston 2012) with the number of qualifiers in 2012 (for Boston 2013) from 22 different marathons, covering more than 108,000 finishers, using results complied by MarathonGuide.com.

If I use the results from all 22 races, there's a drop of almost 50 percent in the qualifying rate. However, most of that drop comes from the Boston Marathon itself. Boston normally has a disproportionate number of qualifiers for the simple reason that most runners who aren’t fast enough to qualify aren’t allowed in, but those numbers were hit hard by the brutal heat in 2012.

If I leave out the Boston results, the drop in the BQ rate is only about 20 percent (see chart below). The remaining 21 races still include over 81,000 finishing times, about 15 percent of the total number of marathon finishers in the US in recent years according to Running USA. That should be a large enough sample to make the results reasonably accurate.

The most important question for any runner—how does this affect my chances of getting into Boston?—remains unanswered, but a 20 percent drop in qualified runners has to help. With any luck, it’ll be enough to ensure that this year, any runner who has already run a BQ time when registration opens will be able to get into the race.

Ray Charbonneau is the author of "Chasing the Runner's High" and "R is for Running". His articles on running have appeared in the Boston Globe, Ultrarunning, Marathon & Beyond, Level Renner, and other publications. He runs with the Somerville Road Runners and he’s finished the Boston Marathon four times. For more info, visit www.y42k.com or email writeray@y42k.com.