For all the fanfare around Apple’s new research platform, questions remain about the quality of data to be collected on the health of iPhone users.

A lot more people may take part in scientific studies, but will the medical information they give be accurate and useful?

That’s one of a number of questions surrounding ResearchKit, the software platform unveiled this week at Apple’s tech gala in San Francisco.

Apple executives hope the open source ResearchKit will leverage the power of millions of iPhone users to strengthen medical research.

“ResearchKit gives the scientific community access to a diverse, global population and more ways to collect data than ever before,” said Jeff Williams, Apple’s senior vice president of Operations, at Monday’s event.

The idea behind ResearchKit is simple.

Apps built on this platform will gather data from the iPhone and certain connected devices. This could include a user’s weight, blood pressure, and activity level. With an iPhone user’s permission, the information will be passed on to doctors and scientists for use in medical research.

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For all the flash of Apple’s announcement about transforming the way medical research is done, there are several outstanding questions about ResearchKit.

Key among them is the quality of medical information researchers will gather through these apps.

For example, scientists don’t have a way to verify that people using an app for asthma or heart disease actually have those conditions.

In addition, data collected by a device still needs to be translated into a clinically useful form.

David Haddad, co-founder and executive director of Open mHealth, which builds mobile health tools, said an iPhone might record the number of steps a user takes in a day. However, that information still needs to be translated into something like “time spent doing moderate-intensity activity” to match up with other similar data.

Haddad’s apps reference clinical standards when gathering information, so when they say “blood glucose,” they have an internationally recognized standard for what that specific measurement means.

But overall, Haddad feels data measured automatically by the iPhone or attached devices like a pedometer or glucose monitor can be more consistent and reliable than information filled out by users.

“I think that it’s obviously going to be much better if the data is collected passively,” he said. “The quality’s better, it’s more consistent, you’re going to have less variability.” Users of iPhones are also not a representative cross-section of a population. According to the Pew Research Center, in 2013 iPhone users were more likely to have higher income and education levels than Android phone users. This kind of bias can make it difficult for researchers to say their findings apply to all groups of people.

The open source nature of ResearchKit, though, may one day allow researchers to collect data from a wider swath of the population.

“By making it open source, I think there’s a great opportunity to take that and adapt it so it can bring in Android data or other types of data,” said Haddad. Over time, researchers may learn how to address these shortcomings, especially if they expect their findings to stand up to peer review or the approval of the Food and Drug Administration. But some researchers are hopeful the apps will encourage people to take a more active role in their health.

“Preventive medicine hasn’t worked by having doctors make to-do lists for their patient, then seeing them six months later and hoping they did everything on the list,” Dr. Michael McConnell, a professor of cardiovascular medicine at the Stanford University School of Medicine said in a press release.

“The future needs a much more ongoing engagement with people’s health,” he added. “We need to understand how to reach out to modify behavior long before we end up having to see someone for a heart attack or stroke.”

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A handful of universities, including Stanford, have already developed apps based on the framework being used by ResearchKit. These join a field that includes other health-tracking tools, such as Fitbit Inc.’s wrist wear.

These kinds of apps and devices can collect enormous amounts of data on a user’s health and activity levels. This is a data gold mine for researchers, who often struggle to recruit enough participants for their studies.

“The more people who contribute their data, the bigger the numbers, the truer the representation of a population, and the more powerful the results,” said the American Heart Association’s Eduardo Sanchez in a statement from Apple. “A research platform that allows large amounts of data to be collected and shared — that can only be a positive thing for medical research.”

This larger group of potential research subjects can also easily download and use the apps, which are often free.

“Now we can reach all corners of the globe to recruit research volunteers and conduct medical research with sample sizes that are orders of magnitude greater than previously possible for a fraction of the cost,” Eric Schadt, a professor of genomics at the Icahn School of Medicine at Mount Sinai, said in a press release.

The school, in a partnership with LifeMap Solutions, developed the free Asthma Health app to help people monitor their asthma symptoms and follow their treatment plans.

Dr. Euan Ashley, professor of cardiovascular medicine and genetics at Stanford University School of Medicine, says that apps like Stanford’s MyHeart Counts are important tools for viewing a person’s health in greater detail.

“We have known for years that physical activity is more powerful than any medication in saving lives,” said Ashley in a press release, “but now we can measure physical activity so much more accurately.”

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