HaD Pop.txt

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Author:
hh123
ID:
57275
Filename:
HaD Pop.txt
Updated:
2010-12-27 05:02:44
Tags:
had pop
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Description:
semester 1
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  1. What types of bias are there?
    • Information bias
    • Recall bias
    • Selection bias
  2. What is information bias?
    • Differences in measurement in the groups
    • Correct people wrong info
  3. What is recall bias?
    Differences in the groups due to forgetting info
  4. What is selection bias?
    Wrong people correct info
  5. What is confounding?
    A factor associated with the exposure and disease of interest but not itself on the causal pathway
  6. What is Incidence rate?
    Number of new cases of a disease in a defined population in a defined period of time
  7. What is prevalence?
    Proportion of people affected in a defined population at a particular point in time
  8. What is a cohort study?
    • 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
  9. What is a case control study?
    • 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
  10. What is a randomised control trial?
    • Comparison of two treatments interventions or a placebo chance determins who gets what and it is planned
    • Can be ethical problems
  11. What is a systematic review?
    • Overview of primary studies that used explict and reproducible methods
    • Uses bradford hill criteria
  12. What is a meta-analysis?
    Mathematical synthesis of two or more primary studies that addressed the same hypothesis in the same way
  13. What are the advantages of a systematic review?
    • 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
  14. Limitations of systematic reviews?
    • Dependant on quality of primary studies
    • Susceptible to publication bias
    • Reader still needs to consider generalisability of the result
  15. What is the observed incidence rate ratio?
    =observed incidence rate in pop 1/ observed incidence rate in pop 2
  16. What is the odds ratio?
    • Measure of the risk of disease in one group compared to another
    • =exposed disease x unexposed no disease/unexposed disease x exposed no disease
  17. What is the standard mortality ratio?
    • = (observed/expected)x100
    • Smr >100 means more incidence than expected
  18. What is the error factor?
    • Measure of random variation
    • Large error factor can be due to small sample size
    • = exp(2xsquare root[(1/d1) + (1/d2)])
  19. What is the 95%confidence interval?
    = from the obseved value / error factor to the observed value x by the error factor
  20. What is the p-value?
    • 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
  21. What is evidence base medicine?
    • 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
  22. What are the levels of evidence?
    • Systematic review of RCTs
    • RCT
    • Well designed trial
    • Well designed non experimental study
    • Respected authority

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