Is this accurate?

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Hello! I have a stair-climber that I use for my cardio but it doesn't appear to be listed under the excercise directory so I've been using the 'stair-treadmill ergometer' versus the walking option, as it is more vigorous than walking or at least feels that way. (Ten minutes of walking, even at 4mph doesn't quite get me up to the sweat I get going on this little guy) However I was wondering if this was an accurate representation of the calories I burn per work-out as it is in fact NOT a treadmill and while it has an ergometer attached to it I'm afraid to say that I don't quite understand how it works as we appear to have misplaced the manual.

For those who are unfamiliar with what I'm talking about I'm essentially referring to this-->http://www.exercisegoals.com/stair-stepping-and-climbing.html

Thank you for your time!