Given a student's grade at t1, t2, t3, etc., we formed a variable for duration of the SET programme (number of years). (academic.oup.com)
This however isn't a cause for concern for Olympic Lifters because of the short duration of their sets. (fitnessandpower.com)
Relations between duration of SET / No - SET and the outcome variables, with raw scores on the vertical axes and number of years on the horizontal axes. (academic.oup.com)