Is daylight saving time the ultimate in efficiency, or is it living a lie? Here are some graphs that might help facilitate a discussion on this topic ...
With daylight saving time (DST), a whole geo/political area (such as a country) decides to set their clocks forward an hour during the 'summer' months (when the sun rises earlier and sets later) so that they can take advantage of the extra sunlight hours, without all the factories/stores/etc having to change their hours of operation.
Not all countries honor DST, and in some cases not even all the areas within a country agree to honor it. Here is a world map I created with SAS (similar to one I saw on dadaviz) that shows which areas do and don't honor DST. In general, it looks like most of North America and Europe honor DST, and countries that are close to the equator or in Asia tend not to.
Of course, it's not as easy as saying a country does or doesn't use DST -- different countries can also choose when they want to start and stop DST! For this part of my graphical analysis, I've created some graphs only for the US DST. But even plotting the data for just the US is a bit tricky, because when we start & stop DST has changed over the years. For example, in 2007 the date to go on DST moved from the first Sunday in April to the second Sunday in March, and the date to go off DST moved from the last Sunday in October to the first Sunday in November. Here's the calendar for the current year (2015) showing which days are/aren't DST days:
Looking at that calendar chart, it appears that we (in the US) are now spending over 50% of the year with our clocks adjusted forward in DST. Let's use a different chart that will make it even easier to see the percentages. We could use a bar chart with 2 bars, but I think a pie chart is more intuitive (a lot of people like to bash pie charts, but I think they are a good/intuitive way to show the data when comparing part-to-whole with a 2-slice pie). From this chart, it's evident that we're spending almost 2/3 of the year in DST!
Personally, I have mixed feelings about DST. I can see the advantages of using it in the summer when days are very long, but I think the US might have gone a bit overboard if we're spending over 1/2 of the year (actually about 2/3 of the year) living a lie and adhering to a fake time.
So, what's your opinion on DST? Does your area honor it? If your area doesn't honor DST, do your factories/stores/etc change their hours in summer and winter?