HaD Pop.txt

• Information bias
• Recall bias
• Selection bias

• Differences in measurement in the groups
• Correct people wrong info

Differences in the groups due to forgetting info

Wrong people correct info

A factor associated with the exposure and disease of interest but not itself on the causal pathway

Number of new cases of a disease in a defined population in a defined period of time

Proportion of people affected in a defined population at a particular point in time

• Identify based on exposure then monitor disease outcome
• Suitable for rare exposures
• Less prone to bias
• Expensive
• Problems with follow up
• Analyse with incidence rate ratio and smr for external comparison
• Can be prospective or retrospective

• Identify on disease outcome and compare exposure
• Suitable for rare diseases
• Cheaper
• Problems with recall and selection bias
• Analyse using odds ratio then estimate relative risk

• Comparison of two treatments interventions or a placebo chance determins who gets what and it is planned
• Can be ethical problems

• Overview of primary studies that used explict and reproducible methods
• Uses bradford hill criteria

Mathematical synthesis of two or more primary studies that addressed the same hypothesis in the same way

• Limit bias
• Increase prescision of overall result
• Large amounts of info can be understood quickly
• Results of studies can be compared
• Reasons for inconsistencies can be identified

• Dependant on quality of primary studies
• Susceptible to publication bias
• Reader still needs to consider generalisability of the result

=observed incidence rate in pop 1/ observed incidence rate in pop 2

• Measure of the risk of disease in one group compared to another
• =exposed disease x unexposed no disease/unexposed disease x exposed no disease

• = (observed/expected)x100
• Smr >100 means more incidence than expected

• Measure of random variation
• Large error factor can be due to small sample size
• = exp(2xsquare root[(1/d1) + (1/d2)])

= from the obseved value / error factor to the observed value x by the error factor

• A measure if how likely the results are due to chance
• If 95% CI excludes the null hypothesis value of 1...
• P<0.05
• reject null hypothesis
• There is evidence of a difference
• Result is not due to chance

• Use of best current evidence in making descisions about the care of individual patients
• Involves the integration of best clinical expertise best evidence from research and patients unique values and circumstances

• Systematic review of RCTs
• RCT
• Well designed trial
• Well designed non experimental study
• Respected authority