Probability Distributions

Question 1

Give examples of discrete variables

Answer 1

Sum of 2 dice
Categorical outcome (yes/no)
Number of mice

Question 2

Give examples of continuous variables

Answer 2

Weight of mouse
Height of person
Fluorescent marker luminosity
Protein abundance

Question 3

What is Gaussian distribution?

Answer 3

Normal distribution
Bell curve
Symmetrical

Question 4

In a pattern of normal distribution, 95% of the data lies between…

Answer 4

+/- 1.96 standard deviations from the mean

Question 5

In a pattern of normal distribution, 99.7% of the data lies between…

Answer 5

+/- 3 standard deviations from the mean

Question 6

In a pattern of normal distribution, 66.8% of the data lies between…

Answer 6

+/- 1 standard deviation from the mean

Question 7

Why is very skewed data sometimes made into a log-normal distribution graph?

Answer 7

To make it look better in a standard shaped (almost) normal distribution

Question 8

Give examples of data given in log-normal distribution

Answer 8

Gene expression (RNA-sequence essays)
Mass spectrometry data
Drug potency

Question 9

Give examples of data which produces Poisson distribution

Answer 9

Count distribution (ie bacterial colony count)

Question 10

What is binomial distribution for?

Answer 10

Data with two outcomes ie yes/no, heads/tails, male/female

Random error

Error of proportion or mean

Question 11

Which distribution does binomial distribution follow?

Answer 11

Normal/Gaussian