Here's the latest quarterly report from Network World and Visual Networks as we look at the top ISPs in the market. Through statistical analysis of Visual's Internet BenchMark data for dial-up service, we ranked the top ISPs in the business-to-business, national and regional markets, as they compare with other vendors within the same market. We've also included results for the past six months, to show whether an ISP's ranking this month has spiked or is consistently above average.
The marketplace seems to be tightening up. In September, AT&T's WorldNet service stayed on top in the national retail market, performing above the industry average in three out of the nine categories tested. BellSouth and SBIS shared the top spot in the regional retail market, and AT&T's Global Network Service (GNS) and UUNET's GridNet service tied for the lead in the business-to-business market. As always, you can check out monthly reports on Network World Fusion.
The data for this report comes from Visual Networks. Through its Internet Benchmark data, Visual Networks rates national, regional and business-to-business ISPs according to several factors, including call failure rate, modem connect speed and Web download performance. We took the raw data from Visual Networks and applied statistical analysis to rate the relative performance of each ISP. First, we derived the standard deviation of the numbers in each performance category. Standard deviation is a measure of how far the numbers in a series diverge from each other.
For each category in which an ISP performed better than one standard deviation from the industry mean, we award it one point. If the ISP did better than two standard deviations from the mean, we awarded it two points. Similarly, if an ISP did worse than the industry mean by more than one standard deviation, we took a point away from its score. If it did significantly worse, meaning two or more standard deviations, we took away two points. We started with a baseline of 12 points, so if an ISP scores 0 points it ends up with an adjusted score of 12.
After we scored each category, we summed the results to get a number that indicated the reliability and performance of each ISP.
A rating of 12 means an ISP was about even with its peers, or the industry average. In September, nine ISPs scored higher than 12 and six ISPs were average. The bad news, however, is that 12 ISPs scored less than 12 points.