Lecture 3 Flashcards
Describe Koch’s postulates
Koch’s postulates are about microorganisms it was focused on a relationship between a causative microbe and disease
List Koch’s postulates (4)
- The bacteria must be present in every case of the disease.
- The bacteria must be isolated from the host with the disease and grown in pure culture.
- The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.
- The bacteria must be recoverable from the experimentally infected host.
List Hill’s criteria
- Study design, its ranked according to their ability to demonstrate casualty.
-strength of association, its the relationship b/w the cause and effect
-Consistency
-Correct temporal relationship, cause must come before the effect
-Dose response relationship between exposure and severity of the outcome, is it reversible and whats the threshold level
-Plausibility, has to make sense with scientific information
-specificity
-analogy- comparing the cause and effect
Stella Dun Can’t Come As She Pees Snakes
Describe Evan’s postulates
everyone is an individual and will not response to the same disease in the same way
Not all causal factors have the same weight
More than 1 factor could be responsible for the disease
What are the steps for epidemiology test
Step 1 come up with the objective of this study
-association between factor and disease and strength of association
Statically signifcance
-difference, is there a big difference
Step 2 what type of data do you have
-is it proportional data or interval/ratio
Step 3 what type of study design are you using observational or experimental they will differ in the end goal
Step 4 are the groups your comparing independent (most cases) or matched (paired, matched characteristics you use a matched study design, therefore using smaller sample size)?
Step 5 choose the best way to analyse data
-epidemiological
-Statistical
-chi-square
-t test
What is RCT
RCT is randomised controlled clinical trial and its used to compare therapies
What is unique to a RCT
- subjects are randomly assigned to comparison groups
- the investigator manipulates treatment
- The investigator compares the subjects studies with an appropriate control group
Why do we need control
- Disease will fluctuates its not at a constant level
- Predictable improvement
- Hawthorne effect (physiotherapy) placebo effect (you think it works and it does)
Define the regression to the mean
Regression to the mean is stats if you take a sample of the population they will have a sample means, you have lots of sample means which will move towards to the total population mean
The more you sample the more then mean moves
When would we not use a control?
You can use the same individual as the control, so measure something and then intervene and measure it again,
a weakness here is the stress measurement and time of the measurement, the large time between the 2 measurement ^creases the chance that the environment and the physiology could change effecting the results
What does random allocation mean?
Every individual has an equal chance of being chosen
Explain the difference between efficacious and effective treatment
Efficacious treat is one the works for those who receive it
Effective treatment is the one that works for those whom it is offered too.
Where do the subjects come from?
It will depend on the study and the money involved, how close is the species to who will actual use the product
What is the weakness of this study design?
Individuals are different, this comes back to sample size, which takes into account the variation between individuals to over come this issues you the cross over design
What is the advantage of this study design
advantage is getting around the individual variation and therefore the sample size is smaller and the animals are getting both the treatments.
