Colorado has been the measuring stick for both supporters and opponents of an initiative to legalize recreational marijuana in Arizona this November.

A recent ad from the Campaign to Regulate Marijuana Like Alcohol, a pro-marijuana group, attempts to show the positive effects of marijuana regulation in Colorado, highlighting millions of dollars going toward public education and the lack of an increase in pot use among teens.

"According to the Colorado state government, marijuana use among high school students has not increased since legalization," the ad, which started airing Sept. 27, claims. We should also note that the anti-pot camp has used Colorado teen pot statistics in their ads.

Colorado legalized recreational marijuana in 2012. The first retail store opened in January 2014.

We have seen multiple numbers on teen pot use, so we wondered if this claim held up.

Barrett Marson, a spokesman with the pro-marijuana campaign, pointed us to the 2015 Healthy Kids Colorado Survey.

The ad cites a June 2016 Denver Post article, which references the survey.

This survey, which takes place every two years, is done by the Colorado Department of Health and Environment. The 2015 version surveys about 17,000 middle and high school students at random.

According to the results, 38 percent of high school students surveyed said they used marijuana at least once their life. In 2013, that number was 36.9 percent.

The 2015 survey also noted that 21.2 percent of high-schoolers used marijuana in the last 30 days. That number was 19.7 percent in 2013.

However, the stats are not significant, according to multiple experts we spoke with. This means the data has wiggle room.

"There was not a statistically significant increase in 30-day or lifetime marijuana use among high school students between 2013 and 2015," said Mark Salley, a spokesman with Colorado’s health department.

The state’s top health official, Dr. Larry Wolk, said the same thing in December 2015 when looking at federal data -- from the National Survey on Drug Use and Health -- on the topic.

The national survey notes that 11.16 percent of Colorado 12- to 17-year-olds in the 2012-13 cycle used marijuana in the last 30 days . That number was 12.56 percent in the 2013-14 cycle.

"This is not a statistically significant increase at the 5 percent level of significance," said Brad Stone, a spokesman with the Substance Abuse and Mental Health Services Administration.

Jonathan Caulkins, a public policy professor at Carnegie Mellon University, said the clock hasn’t even really started on the full effects of legalizing recreational marijuana.

"We’re not going to see the full effects of legalization until something like 25 years after national legalization," Caulkins said. "It takes time for the industry to adapt to new opportunities, go through the usual shake-out period."

Our rating

The ad claimed, "according to the Colorado state government, marijuana use among high school students has not increased since legalization."

Based on the numbers cited, there does appear to have been a slight increase in marijuana use among Colorado’s high school students. However, multiple experts we spoke with said that increase is not statistically significant. They also said it was too early to draw conclusions about marijuana use, and that more years of study will be needed.

We rate the ad’s claim Half True.

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