Making a new variable from existing variables

Duki

New Member
#1
Hi everyone! I have this paragraph from an article
'We next created a scalar variable that incorporated participants’ confidence ratings into their match judgments, which we analyzed using a 2 x 2 (crime type x suspect characteristics) ANOVA. Specifically, we multiplied participants’ match judgments (coded as -1 for no match and +1 for match) by their confidence (1–10) and applied a -/+.5 correction to account for the absence of zero values.' - Smalarz, L., Madon, S., Yang, Y., Guyll, M., & Buck, S. (2016). The perfect match: Do criminal stereotypes bias forensic evidence analysis? Law and Human Behavior, 40(4), 420–429.

Can someone explain to me why it was necessary to create that new variable like that?
Thanks!
 

katxt

Active Member
#2
I'm guessing here. It looks as if they wanted a scale of the "strongly disagree" "no opinion" "strongly agree" type.
The new scale goes from -9.5 to 9.5 where -9.5 means "very confident there is no match", through -0.5 and 0.5 which means "I'm really not sure if there is a match or not" through to +9.5 which means "very confident there is a match" (although I would have described the correction as +/- 0.5). It's hardly likely to be normal.
 

Duki

New Member
#3
I'm guessing here. It looks as if they wanted a scale of the "strongly disagree" "no opinion" "strongly agree" type.
The new scale goes from -9.5 to 9.5 where -9.5 means "very confident there is no match", through -0.5 and 0.5 which means "I'm really not sure if there is a match or not" through to +9.5 which means "very confident there is a match" (although I would have described the correction as +/- 0.5). It's hardly likely to be normal.
Thank you for your response. It really helped!