This function is used to exclude from your chart the interpretration of any temperature measurement that may be erroneous. OvuFriend will not take this measurement into consideration when determining your fertile days and your date of ovulation. Check this box if you suspect that some unusual factors have affected your temperature on a given day, such as illness, changing the time of measurement, or a journey to a different time or climate zone. (What factors may distort the reliability of the basal body temperature measurement?)