My first research question is based on establishing whether mental toughness is a trait like construct or a skill that can be manipulated through training and experience. I am using descriptive statistics. 400 research participants underwent intensive training in 7 mental skills. Pre- and post intervention scores for all 7 mental skills were compared. When calculating the difference between pre- and post-intervention standard deviation scores for each of the mental skills, what information does this provide me with? And difference in variance? I apologise in advance if this is a stupid question - my knowledge of stats is extremely limited!