I wanted to see the effect of daylight saving time change on sunrise and sunset times. The data was taken from http://www.timeanddate.com and is for Chicago. The figure shows that daylight saving time change (marked by the DLS lines) keeps the sunrise time pretty much constant throughout the whole year, while making the sunset time change a lot. The spread of sunrise times for the whole year as measured by the standard deviation is 42 minutes, while for sunset times is 1:30 hours.