Government officials and researchers are gathering in Washington state this week to discuss the impact of marijuana legalization, the Associated Press reports.

Participants say it is important to look at how legalization affects issues ranging from school suspension rates to traffic deaths. The conference is being sponsored by the Washington Office on Latin America, along with the Washington state chapter of the American Civil Liberties Union.

“The real purpose … is to be sure we’re doing the best we can to evaluate the impacts,” said John Walsh, with the Washington Office on Latin America. “We want to learn from the pioneers for the pioneers, but be more systematic about what we know and what we still need to learn so the jurisdictions that are coming next can avoid mistakes and do an even better job.”

Officials from states where recreational marijuana is legal—Washington, Colorado, Oregon and Alaska—are attending the conference, as are those from Vermont and California, where votes are expected on legalization in 2016. Participants have come from Uruguay, the only country that has legalized the adult use of marijuana. Mexico, Jamaica and Colombia are also represented.

Washington is conducting a cost-benefit analysis on marijuana, which was required by the state’s legalization law passed in 2012. The state is tracking and analyzing data on marijuana-involved traffic stops, admissions to addiction treatment centers, and marijuana-related calls to the state’s poison center.

Colorado officials are also tracking poison control calls, marijuana-related school suspensions and impaired driving cases, as well as marijuana-related hospital visits.

Dr. Kathy Lofy, Washington state’s top public health official, noted there are challenges in collecting marijuana-related data. She said it is not clear how to identify marijuana-related auto accidents. She noted there is limited data on long-term marijuana use, and there is no consensus on how to survey people about new ways of using the drug, such as eating or vaporizing it.