Back in early January, wireless optimization firm Arieso released a report on the bandwidth usage profiles of various smartphones and other devices. It noted a surge in download and upload usage for the iPhone 4S, moving the new phone ahead of the iPhone 4 and various Android devices to take over the top spot for smartphone bandwidth consumption. At the time, coverage by Reuters (reiterated by several sites, sorry to say, including TUAW) put the onus for this bump in the pipe on one of the marquee features of the 4S: the voice-controlled digital assistant, Siri.

Fast forward a few weeks: an op-ed from Paul Farhi in the Washington Post dives back into the Arieso report, recycling the charge that Siri is singlehandedly responsible for pumping up the load on America’s cellular networks and degrading data service for everyone. (Farhi stopped short of blaming her for fluoride in the water and the rise of reality television.)

This time, however, some consideration of the facts in evidence led us to question his (and our) original conclusions; we don’t know whether he came up with the idea independently or based his column on the Reuters coverage, but we know that the math around Siri’s data usage just doesn’t add up to a consequential amount. We also reached out to Arieso for a copy of the full report, which the company happily and promptly provided.

Now there’s another voice weighing in, and it belongs to someone who’s in a position to know what’s what: former Siri board member Gary Morgenthaler. He wrote a guest post for Forbes’s web site that thoroughly debunks the notion of Siri as a bandwidth bandit. Siri actually uses only small bites of wireless data, as tested by Ars Technica and backed up by Morgenthaler’s inside info.

What does Morgenthaler suspect might be at play in the 4S bandwidth numbers? He’s careful to couch it as speculation rather than assert it as fact, but the addition of iCloud to the iOS service mix is a likely culprit (especially since buyers of new phones are more likely to set up Apple’s cloud service than users of older models, who may be slower to update to iOS 5). Other possibilities include iTunes Match, Photo Stream, or simply the wider chunk of image data captured by the iPhone 4S’s improved camera. As Mel noted earlier, the 4S also supports faster 3G downloads than the earlier models.

There’s only one factual flaw I saw in Morgenthaler’s response, but it’s an important one. Morgenthaler suggests that Arieso committed a logical error in citing Siri as the cause of the 4S results:

Arieso presents no data to support their claim that Siri causes the increase in iPhone 4S data usage. Most likely, Arieso committed a logical fallacy which, in grammar school, was called “post hoc, ergo propter hoc” – that is, “after the fact, therefore, because of the fact.” In other words, Siri is new and associated with the iPhone 4S; therefore, it must be the cause of this increased traffic. It’s an appealing argument, but it doesn’t hold water.

That’s also an appealing argument, but he’s pinning the propter hoc on the wrong donkey. Even a cursory review of the Arieso report is sufficient to discover that it does not mention Siri at all. When it comes to the cause of the iPhone 4S’s download hunger, in fact, the report makes it very clear that it’s too soon to draw any specific conclusions (emphasis mine):

The iPhone 4S showed an increase of 176% in downlink data volumes over the iPhone 3G. Since the downlink-to-uplink data volume ratio was almost 7-to-1 on average for the devices under study, this downlink increase of 176% corresponds to a larger total volume of data than a 220% uplink increase (discussed in the last section). As noted earlier regarding the increases in total numbers of data calls, it remains a topic for further study to characterise the root cause of this downlink data volume increase.

Arieso never said Siri was to blame, at least not in so many words; it’s not clear whether a company representative said something to Reuters to encourage this conclusion, but it’s clearly not backed up by the report itself. Did the firm make an effort to correct the record, or was there a calculation that the Siri-related publicity would be more valuable than getting the accurate information out? We don’t know, but we’ve reached out to Arieso’s PR folk for comment.

Meanwhile, we’re left with the unavoidable conclusion: The Washington Post and Paul Farhi picked a fight with Siri for something she does not do, picking up the “Siri is a data guzzler” concept from the Reuters story, from confusion or from imagination — but not from the actual data. Hanging the 4S bandwidth bulge on an innocent intelligent assistant may be great for headlines, but it looks to be wrong on the facts.

Siri VC Morgenthaler weighs in on iPhone 4S bandwidth badmouthing originally appeared on TUAW – The Unofficial Apple Weblog on Mon, 30 Jan 2012 12:30:00 EST. Please see our terms for use of feeds.

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