lack of valid consent

• ask for full valid consent prior to research, and offer participants the right to withdraw at any stage, (this may impact validity.)
• ask participants for retrospective consent after debrief on the aims and details of the study - offer the opportunity to withdraw their data if they wish.
• gain presumptive consent - asking a group of people with the same characteristics as your participant if they would consent. If they do, you can presume your sample would feel the same.