Distribution of Swine Flu Cases by Weekday 

 How will you expect swine flu cases to be distributed by weekday? More specifically, will you expect more cases distributed in weekdays or in weekends? My first reaction is that there will be more cases if there are more social gatherings. 

 Following this logic, the reasons for supporting more cases in weekdays may include that susceptible population have more contacts with infected population in weekdays, either through school or through work, etc. In addition, as people are more likely to travel in weekends, it means that they will have more contacts with infected subjects during their traveling, but because it takes around two days for the virus to have impacts, the cases will not be identified until a couple of days later. Could this also be due to the fact that there are less clinical services provided in weekends and that people are less likely to visit clinics in weekends? 

 Here is   an old graph    I made according to the swine flu updates (4/26/2009 - 05/21/2009) published on  WHO's website . To be more accurate, I drew   a new graph   using the number of confirmed new cases rather than the cumulative number of confirmed cases. 

 As the reporting times for confirmed new cases vary, some at 18:00 while others at 6:00, etc., I kept only records between 05/01 and 05/21 whose reporting time is at 6:00 and redrew the graph. Weekdays are redefined as well. For example, Thursday 6:00 to Friday 6:00 is defined as Thursday. Could you still see any salient patterns, like the differential between weekdays and weekends? Why Friday is so spiky this time?