It has been widely quoted that from past records, the Dow ends up positive 70% of the time when January was an up month and 90% of the time when its first 5 trading days are positive, which is what happened this year. However the Dow lost its gains and finished -3.7% for the month, signaling that a major trend change could have occurred in the middle of the month.
Not so sure about the reliability of the second statistic as the sample size is probably much smaller- the number of years beginning with 5 consecutive up days is certainly much smaller than the number of positive January months.
Perhaps a better way to refine the statistics would be to check on the years where the Dow fulfills these criteria (which is what happened this year) and check the % of years where it was :
-Up for first 5 trading days of the year
-Down for January
On a separate note, February is quite a neutral month for the STI.