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Rachel S.
Senior Epidemiologist and Biological Sciences Tutor
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R Programming
TutorMe
Question:

Using a pre-existing dataset, how would you create a new variable?

Rachel S.
Answer:

For creating new variable assignment operator ‘<-’ is used (although it is also totally ok to use "=" if this is what you are used to from using other programmes!) Use the "$" sign to define the name of your new variable, and to direct R as to how you would like to calculate it. For example... mydata$sum <- mydata$1 + mydata$2 This will create a new variable called "sum" within "mydata", using the addition of 1 and 2.

Public Health
TutorMe
Question:

Describe the general features of a confounding variable.

Rachel S.
Answer:

A confounding variable is a variable, or exposure that is associated both with a disease and with a causative agent that you are studying. A confounder should not be a variable that is "on the disease pathway‟ as that would be considered as an “effect modifier”. Confounding variables can increase the association between an exposure and an outcome, or decrease the association (i.e. they can be “positive” or “negative” confounders).

Biology
TutorMe
Question:

Explain fully why the number of antibiotic-resistant populations of bacteria is increasing.

Rachel S.
Answer:

The overuse of antibiotics leads to antibiotic resistance being a selective advantage. Genes for antibiotic resistance can spread easily between bacteria and between populations. Mutation rates in plasmids (where the gene is located) can be rapid Bacteria can reproduce rapidly thereby increasing the numbers of antibiotic-resistant bacteria populations, which is a risk particularly in immuno-compomised patients.

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