Individual Differences: Psychometric Tools *lecture notes*

Individual Differences: Principles of Psychomerric Tools by Dr Michael Manrzios

- Reverse scoring of negatvely keyed irems
o If a questonnaire has positvely and negatvely keyed irems
o Negatvely keyed irems musr be reverse scored
o Before checking rhe scale’s psychomerric propertes
o And before doing sratstcal analysis
- Advanrages of odd-numbered scales
o Appealing ro respondenrs
 Easy opton ro selecr presenr
o If ropic is sensitve
 Besr ro offer a neurral poinr
- Disadvanrages of odd-numbered scales
o People may be less discriminatng in response
 Don’r rake tme ro consider differenr responses
o May nor be collectng accurare response
 Mid-poinr can mean differenr rhings ro differenr people
- Advanrages of even0numbered scales
o People may be more discriminatng
 More rhoughtful
o Eliminares possible misinrerpreraton of midpoinr
- Disadvanrages of even-numbered scales
o Respondenrs could become frusrrared
 And nor complere rhe survey
o May nor be collectng accurare responses if respondenrs perceive being
required ro make a selecton

- Principles of Psychomerric rools
o Essental crireria for a good psychomerric resr
 Validiry
 Depends on rhe purpose
 ‘rhe purpose of resrs’
 does ir measure whar we rhink ir measures
 Reliabiliry
 ‘consisrency’
 does ir show consisrenr resulrs