This filter checks the standard deviation of ticket's main numbers. Standard deviation is a mathematical formula, which evaluates how close are the ticket numbers to each other. Low standard deviation values mean that ticket numbers are very close to each other in the number pool. High standard deviation values mean that ticket numbers are from different parts of number pool.
Ticket numbers 1-2-3-4-5-6 have standard deviation of 1.87. The value is low because all numbers come from the same section of number pool. The same applies to ticket numbers 44-45-46-47-48-49 which have also standard deviation of 1.87.
Ticket numbers 6-9-15-18-33-43 have standard deviation of 14.43 because the numbers come from various parts of number pool.
See also Standard Deviation statistical property.