Masters Time Rating Explanation The best indication available today of swimming speed as a function of adult age is the set of FINA masters world records (SCM, LCM) and USMS National records (SCY). The rating system presented here uses a least squares parabolic curve fit to the masters National / World records from age 25 to 80 to establish a distinct record curve for each pool event. The purpose of the curve fit is to smooth out anomalies that occur when one or more age group world records are disproportionately strong, or weak, compared to others. Example: Click Here to see the graph of the women's SCM 50 breaststroke world records (11/05) as a function of age. The masters time rating is calculated by taking the ratio of the record curve time (total seconds) at the swimmers age divided by the swimmers time, and multiplying that by one hundred . The FINA world records and USMS national records used in these programs will be updated approximately once a year. The programs presented here derive record curves from the World / National record times in this database. Therefore the record curves for each event will change each time the World / National records are updated. Due to the demographics of those who competes in masters competitions versus those who stay active in open swimming competition there are some events where the 25-29 age group world record is slower than the 30-34 or even 35-39 age group world record. This creates the unlikely scenario where the world record curve shows a minimum at an unexpectedly high age. Therefore, if the record curve minimum occurs at an age greater than 25, then that minimum time value is used for all ages below the age at which the time minimum occurs. NELMSC calculation age: Most swims in the NELMSC database have the swimmers age recorded. Some swims just have the age group with no specific age. For these swims the lower bound of the age group is used for the calculation. NOTE: This rating factor is intended to provide a means of comparing swims done by men and women across the masters swimming age groups and from masters swimming competition. This rating factor is not intended to compare swim times from youth programs to masters swimming competition.