I believe quicksilver gave an excellant reply.I have purchased the Prime Times calenders for the last two years.Their primary premise is to let you know when the moon is either directly over head or directly under foot.If those times correlate with peak movement times(dawn and dusk)then they predict those times of the month to be the most favorable.I do believe that there is certainly some validity to them and it is another thing to consider within all the other influences.