FORTUNE — The folks at the Chitika ad network set out last month to test whether Microsoft’s (MSFT) Surface — heavily promoted as the tablet best suited for doing real work — is actually being used more in work settings than Apple’s (AAPL) iPad or all those tablets that run Google’s (GOOG) Android.
To find out, they analyzed tens of millions of North American ad impressions between Jan. 20 and Feb. 2 and produced the pair of charts attached above and below.
Among their findings:
- The iPad rules. During the peak hour for tablet Web usage in North America – 9 p.m. Eastern — the iPad generated four times the traffic volume of all the Android tablets combined and vastly more than Microsoft’s Surface. (See top chart, showing relative usage share where iPad = 100%.)
- Androids more like iPads. Their hour-by-hour usage patterns differ by no more than 6% in any hour; the average difference over 24 hours is 0%. (See bottom chart, showing relative share where peak hour for each device = 100%.) The differences were more pronounced in a Chitika study last summer that combined tablet and smartphone usage.
- The Surface has slight 9-to-5 edge. Although Surface usage dropped off a bit more during non-work hours, Surface owners, like everybody else, tend to peak at 9 p.m., well after after the workday is over.
“Despite the usage statistics presumably indicating some success for Microsoft in this area,” the report concludes, “the company has a long way to go before challenging Apple or Google in terms of raw usage volume during working hours.”
CAVEAT: These charts are for North America only.