The new year brings new forecasts. While it does seem as if the prognosticators are getting more accurate, or at least on the same page, forecasting an immature market like mobile health remains an inexact science.

Business market intelligence company Transparency Market Research, Albany, N.Y., just came out with a report saying worldwide sales for mobile health technologies and services will reach $10.2 billion by 2018, up from $1.3 billion in 2013. That represents an average compound annual growth rate of 41.5 percent.

Also just off the presses is the Deloitte Center for Health Solutions' report, "mHealth in an mWorld: How mobile technology is transforming health care," which has remarkably similar findings. Deloitte says the same market would rise from $1.2 billion in 2011 to $11.7 billion by 2018, at a compound annual growth rate of 39 percent.

After that point, the reports start to diverge. Transparency Market Research says "monitoring services" accounted for 63 percent of all mobile health revenue in 2012. If the same ratio holds this year, that market segment would be worth $819 million.

For its part, Deloitte says the market for wireless health monitoring devices just in the U.S. has doubled in the past four years, to $7.1 billion, and is expected to triple to $22 billion by 2015. That's apples and oranges, for sure, since wireless monitoring includes not just mobile apps and the devices connected to smartphones, but in-hospital telemetry monitors and other non-consumer items.

But recall that in March 2012, iData Research reported that the U.S. market for patient monitoring was just $3.1 billion the previous year and would grow at a substantially slower rate than others had suggested, to $4.2 billion in 2018. Around the same time, GBI Research reported numbers similar to those of iData Research, though on a global scale.

Meanwhile, Berg Insight just came out with a study saying that 2.8 million patients around the world were using home monitoring services and devices with "integrated connectivity" at the end of 2012. That means the devices had integrated chips to send data directly to in-home communication hubs or even directly to caregivers over cellular networks, since the figure excludes people using personal mobile phones, tablets or PCs as a conduit. Berg Insight says this number will grow by 26.9 percent annually to 9.4 million in 2017.

There were about 730,000 cellular-enabled devices in use for remote patient monitoring in 2011 and 1.03 million next year. But expect to see an explosion to 7.1 million by 2017, representing a CAGR of 46.3 percent, according to Berg.

That is a high growth rate, but Berg's raw numbers are still rather small compared to what Deloitte foresees among all "embedded medical monitoring gadgets," including those that communicate with smartphones, tablets and PCs. Deloitte says there will be 170 million such devices in use around the globe by 2017.

All of these forecasts make for great headlines, and you can be sure to see some of these predictions on PowerPoint slides this year as conference speakers try to explain the vast market potential. But whom should you believe?