FORTUNE -- Piper Jaffray's Gene Munster has been analyzing Twitter comments and polling a group of more than 800 consumers to try to gauge demand for Apple's (AAPL) iPhone 5. On Thursday he released his latest findings:
The chart below compares buying trends of the iPhone 5 with the iPhone 4S in the 2.5 months after launch based on an analysis of Tweets that contain the keyword "iPhone" and such purchase-related keywords as "bought," "shipped," "purchased," etc. According to Munster, it shows the iPhone 5's "demand index" up 30-40% year over year.
"More specifically," he writes, "over the past two weeks, the demand index is up an average of 36% y/y and we note that this is the iPhone 5 demand ahead of Christmas, when some may be waiting to be gifted the device, compared to the 4S, which would be in January given the 2.5 month comparison. Our 45 million unit estimate assumes 21% y/y growth in iPhone units, thus the demand survey gives us continued confidence in our 45 million unit estimate."
The Twitter chart:
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