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Work in the media? Struggle with statistics? Stan's irreverent (and often irrelevant) review of the latest media reports, news and gossip may not help at all... Stan the Statistician

Stan # 86: Dates - something to chew on! March 2007

"All I ask is a chance to prove that money can’t make me happy" - Spike Milligan
"A hunch is creativity trying to tell you something" - Frank Capra

Those of you chomping at the bit to discover which towns in the UK have a cathedral but are not cities will be dying to know that they are Blackburn, Brecon, Bury St Edmunds, Chelmsford, Guidford, Rochester, Southwark, Southwell and St Asaph. Some time ago, I featured a piece on the calendar which proved very popular with a couple of my readers. I therefore thought I would expand on this theme.

Most people in the World would simply say that the year is 2006 AD. Some would prefer to use the Jewish calendar and say that the year is 5766. Others choose the Islamic calendar where the year is 1426. Each of these refers to the number of years since the origin of a particular religious faith. To use the letters AD after the year implies acceptance of the Christian faith as it stands for Anno Domini which for those of my readers who are not Latin scholars means, ‘in the year of our Lord’. The letters BC also imply acceptance of the Christian faith as they mean Before Christ - no Latin here.

The calendar that we normally use has not been consistent over the last 2,000 years. We are now using the Gregorian Calendar (from 1582) which superseded the Julian Calendar. The former was named after Pope Gregory and the latter after Julius Caesar. However, this doesn’t mean that these two guys had their picture on them. So, if you have a pin-up calendar featuring Jennifer Lopez, you can’t call it a J-Lo Calendar in the same way. The current Calendar was first proposed by the Neapolitan doctor, Aloysius Lilius, and was decreed by Pope Gregory XIII who wanted it to be named after him. Interestingly, there was no year zero. Many non-Christians are happy to use the current counting system because it is in such widespread use but prefer to call them CE for Common Era. A year in the Gregorian Calendar is much closer to the Sidereal Year than those used in the Jewish or Islamic calendars. The Sidereal year is the length of time it takes for the Earth to travel around the Sun and return to the same point. As this takes about 365.25636042 days, it is not possible to keep an exact amount of days in a year without accepting seasonal drift otherwise we would eventually enjoy winter in July and summer in December (in the northern hemisphere of course). A good approximation is to keep 365 days for most years and have a leap year with one extra day every four years. Another adjustment was made in 2005 as a leap second was added. The last minute of the year was 61 seconds long. Did you do something special with it? The Jewish calendar makes corrections in a rather different way. It is based on a 19 year cycle of 235 lunar months but includes solar corrections. There are normally 12 months in a year as in the more common calendar and these are of 29 or 30 days. Three of these can be either 29 or 30 days long with the rest being fixed.A typical year lasts for 353, 354 or 355 days.

To add to the complication of synchronising a Lunar-based calendar to a Solar-based year, a leap year is included seven times in each cycle of 19 years. In these leap years, it is not an extra day that is added but an extra month. The Islamic calendar is purely lunar-based. There are 12 months in each year so that much is common to the Gregorian calendar and to most of the Jewish years. As it is based on visual observations of the moon, it is possible for differences in the calendar to occur in different parts of the World. The year is not locked to the solar cycle so it does drift in comparison to the others. An Islamic year is typically 11 days shorter than the Gregorian. This system dates from 622 AD or CE in the Christian calendar which was based on the Julian calendar at the time. Since then there have been 1,384 years on the Christian calendar but 1,426 years on the Islamic calendar. In which year will the two coincide? Answers on my next desk top.

Sometimes the Islamic year falls entirely within the Gregorian year. For example, 1429 Islamic will fall entirely within 2008 AD or CE. This happens once every 33 or 34 Islamic years (32 or 33 Gregorian years). It’s less easy to find a numerical value for the Chinese years as there are more than one possible starting dates. According to certain explanations, 2006 is either 4643rd or 4703rd year since counting began. Better to use the animals instead. 2007 is the year of the pig with the element of the year being fire. I guess that means roast pig is favourite for the barbies this year.sed figures which show that men who live in East Dorset live for an average of 80.1 years whereas those who live in Glasgow City manage only 69.1 years. I doubt we'll see an exodus though because, of course, the Glaswegians will bring the lifestyle that causes their truncated lives with them. Oddly, the most popular spirit in Glasgow is vodka.

Before 1834, the Bank of England observed about 33 saints' days and religious festivals as holidays but in 1834, this was drastically reduced to just four. They must have had a department dedicated to finding obscure saints to celebrate and they got rumbled.

Check in again at my desk soon!

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