The fоllоwing is аn excerpt frоm а New York Times аrticle; Naps May Be Good for a Baby's Learning by Nicholas Bakalar. The article appeared on January 12th at 3pm. " Researchers tested 6- and 12-month old babies using a puppet with a removable mitten containing a bell. The experimenter engaged the child, then removed the mitten and shook it three times to demonstrate its sound and movement, and replaced the mitten on the puppet’s hand. She repeated the procedure several times. The study was published in Proceedings of the National Academy of Sciences (Links to an external site.). On average, the infants napped for 106 minutes during the ensuing four hours. But 21 of the 40 babies slept 30 minutes or less. The next day, after all the infants had slept soundly for the night, the researchers presented the materials again to see if the infant would remember and try to reproduce the mitten procedure. The babies who had taken long naps after the teaching session were significantly better at reproducing the procedure than those who napped less than 30 minutes." Are the "21 out of 40 babies(52.5%)" in this study- the statistic or the parameter?