Letter: National Grid’s statistics do not tell the whole story

Posted 1/6/21

As the saying goes there are lies, damn lies and statistics. Unfortunately the National Grid data regarding electrical outages in Barrington may fall under all three. (Barrington …

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Letter: National Grid’s statistics do not tell the whole story

Posted

As the saying goes there are lies, damn lies and statistics. Unfortunately the National Grid data regarding electrical outages in Barrington may fall under all three. (Barrington Times December 30, 2020: “There have been worse years for power outages”). The happy face put on by National Grid may not be so wonderful had they provided more information.

Unfortunately delving into this necessitates examining some (dreaded) statistics. To keep things simple let’s confine consideration to just two: arithmetic average and median average. The arithmetic average is the sum total of events divided by the total number of events. The median is the midpoint value for all the events. For an illustration review a series of nine households’ total electrical outages in one year arranged as follows:

0-0-0-0—3—3-3-3-3

The arithmetic average is 15 divided by 9 which equals 1.67. The median average is 3 (the middle value). If you only report the arithmetic average (1.67) it doesn’t sound too bad (although zero is preferable). But if you report the median (3) that’s fairly disturbing. Furthermore in this series 5 of the 9 had 3 outages and that severity is ignored by reporting the arithmetic average alone.

National Grid does not provide median averages.

National Grid’s statistics also ignore the distribution of outages amongst the populace. They reported that there were fewer total outages in 2020 than the previous three years. However, per our illustration above, it is highly doubtful these were evenly distributed among all customers. Chances are outages recur over and over again at the site of the weakest infrastructure. So it is probable that the same customers are affected repeatedly. Therefore we don’t know who is spared and who is not. Our neighborhood had at least four prolonged outages if my recollection is correct. I suppose it’s comforting for the Town of Barrington as a whole to know that the arithmetic average is improved but not for those of us above the median average.

The statistics on the frequency of outages is similarly incomplete. These are also arithmetic averages rather than median averages so the same distortion as seen with total outages pertains here as well. Some customers are getting a raw deal and many, if not most, are scot free (bully for them).

Finally the average duration of power interruption can be skewed similarly. This is a bit more complex because the frequency of outages and the time of them play an overlapping role. We must also know what qualifies as an outage. This has not been defined. If it is only one or two minutes long it may go unnoticed by the customer but still be registered as an outage. Hundreds of brief outages will be of insignificant practical concern but may play a huge role when National Grid adds up the total time of outages. In 2020 the average (again not the median) outage was 15.69 hours. But there could be a relatively significant number of customers with three day or more outages with most others enduring only a few minutes. The information as presented does not allow us to make any conclusions about this.

Fairly or unfairly National Grid has come under significant fire at the municipal and state levels in the past several years for uneven supply issues. I want it to be clear that I am not piling on nor implying that the company has been disingenuous with their reporting, only incomplete. The statistics released by them is virtually useless in determining practical customer impact. They should report the total number of customers who sustained one, two, three or more outages. The range of duration of outages for those customers affected from only a few minutes to multiple days should be reported. Where appropriate the arithmetic averages and median averages should be compared. Worst case and best case scenarios should be provided together with which parts of the town get affected the most, the least, the longest and the shortest. Only if this data is provided will there be any way to judge the truth of the promised future improvements.

Stephen E Glinick

Barrington

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