effectiveness test

• randomization is done to avoid bias
• a blind vs a double-blind experiment to further eliminate the chance of bias
• in a double-blind experiment the researchers are unaware of which treatment group a subject is in. This is a lot of  work but in order to eliminate the effects of other variables other than we like to test besides the treatment (confounding variables) that may affect the results. This is how we draw a cause and effect relation.
• How one chooses to compare or present results can have a dramatic effect on what is implied.

Example: it took too many years to prove the detrimental effects of smoking on health even though there were a lot of results of observational studies.


Some R studio exercise:

Giving data vectors have a type 

>simpsons = c("Jane","John","Ada","Adam")

>names(simpsons)= c("mum,"dad","sister","brother")

simpsons

    mum     dad  sister brother 

 "Jane"  "John"   "Ada"  "Adam"