A graduate student lost her computer with all of her research data, but she was able to find this scrap of paper. Her project compared a group that got a new treatment for PTSD (group A) to a group that got the usual treatment (group B). She knows that the first column in red is for scores on a trauma suppression inventory, and the second column in red is for scores on a negative affect inventory.

Sample size for group A Na 49 49 5 Mean for group A Ma 21.49 15.67 6 Standard deviation for group A SDa 2.62 3.06 7 Sample size for group B Nb 34 34 8 Mean for group B Mb 22.79 17.50 9 Standard deviation for group B SDb 3.49 4.70