1. Study population: Who are you going to measure?
Who is your study population going to be? Decide on the eligibility criteria for the study. You may be guided in including or excluding participants based on such things as their demographics, diagnostic test results, disease duration and progression, disease severity and their medications. In order to obtain a uniform data set, participants must meet all of the inclusion criteria and none of the exclusion criteria. Also consider whether you think their parent or guardian is likely to comply with any intervention or procedures required for the study. For example, in a study examining overweight children the inclusion criteria required the child to have a BMI score classified as overweight or obese according to International Obesity taskforce criteria.
- Where are you going to recruit your participants from and who is going to recruit them? Do you have an existing database of patients to draw on to invite to participate?
- The length of time it will take you to recruit the number of participants required will vary. It may be determined by how frequently you see patients with the disease of interest and you may also need to seek assistance from others to recruit participants.
For APRN Studies you may want to contact us directly to draw upon the casemix data from the Children Attending Paediatricians Study
An important part of your study design is determining what information you are going to collect about:
- study participants (eg. demographics)
- outcome of interest (eg. disease diagnosis, duration, treatment)
- exposure of interest
- parents or guardians
You will also need to decide how often you’re going to measure each variable and who is going to measure it. Keep in mind that the more people involved in data collection means more potential for inter-observer error.
Also some measures can only be repeated after specific intervals for example the Strengths and Difficulties Questionnaire (SDQ) can only be repeated after six months.
Measures relevant to your study may be found in the APRN measures library - http://apps.mcri.edu.au/measureslib
 Wake, M, Bauer L et al, Outcomes and costs of primary care surveillance and intervention for overweight or obese children: the LEAP 2 randomised controlled trial. BMJ, 2009 3 Sep. 339:b3308