Biostatistics

Question 1

Examples of categorical data

Answer 1

Male/female
Pregnant/Non pregnant
Smoker/non smoker

Blood types
non-smoker/ex-smoker/light smoker/heavy smoker/ect

Question 2

What is the likert scale

Answer 2

Type of categorical data

“strongly agree, agree, neither, disagree, strongly disagree”

Question 3

A histogram is used to display categorical data - true or false

Answer 3

False - a bar chart is used because the data is NOT continuous

Question 4

To describe the central tendency of categorical data, what value is used

Answer 4

Median or Mode (NOT MEAN)

Question 5

What is the measure of central tendancy of continuous data

Answer 5

Mean, median and mode

Question 6

In a box and whisker plot, what percentile does each line/part of the box represent

Answer 6

Bottom line of box - 25th percentile
Middle line - 50%
Top line of box - 75th percentile

Question 7

What is the equation of varience

Answer 7

Varience = (value of one observation - mean)^2 / n-1

Question 8

What is the equation for standard deviation

Answer 8

Square root of varience

Question 9

What % of data will lie within 2 SD of the mean

Answer 9

95%

Question 10

On a normal distibution graph (bell curve), what point signifies the mean and standard deviation, respectfully

Answer 10

The peak of the belll curve is the mean

Either side of this is the SD

Question 11

What is a 95% confidence interval

Answer 11

A range which contains the true population mean with a probability of 0.95

99% of the data will be within 3 SD of the mean

Question 12

A positively skewed distribution is skewed in what direction

Answer 12

Left

Question 13

What does the P value describe

Answer 13

The probability of having observed our data when the null hypothesis is true

Question 14

We reject the null hypothosis when the P value is what

Answer 14

less then 0.05

Question 15

In hypothesis testing you are always trying to prove the null hypothesis

Answer 15

True

Question 16

What are 2 dangers of P vales

Answer 16

Over reliance of use of P-values
Misinterpretation of P values

Question 17

We are more likely to find a statistical difference in a one sided test - true or false

Answer 17

True

Question 18

What is type one error

Answer 18

When you choose to reject the null hypothosis when you shouldnt

Question 19

What is a type 2 error

Answer 19

Usually occurs due to small sample sizes

Question 20

What is the main difference between paramtric and non-parametric data

Answer 20

In parametric you are assuming normal distribution.
There are little assumptions in non-parametric tests

Question 21

What are some assumption in T tests

Answer 21

Each pair of observations is completed unrelated to every other pair
Normally distributed
Roughly equal SD of both groups (<2)

Question 22

What is the null hypothesis usually in parametric tests

Answer 22

No difference between the values

Question 23

T tests and one way ANOVA are parametric tests - true or false

Answer 23

True

Question 24

What is the non-parametric equavilent to a T test

Answer 24

Mann Whitney Test

Question 25

What measure of central tendancy is used in Mann Whitney Tests

Answer 25

Median

Question 26

When is a one way ANOVA test used

Answer 26

To compare the continuous variable in three or more independant groups

Question 27

How do you calculate risk between two categories

Answer 27

Number of people (people who got flu after vaccine)/total number of people in the whole category (everyone that got the vaccine)

Question 28

When would you use a fishers test over a chi square test

Answer 28

If the sample size if no big enough for the chi square, use the fisher

Question 29

If there is a P value < 0.05 in a chi square test, what does this tell us about the risk between the two values

Answer 29

There is evidence that the who categories related in risk (e.g eyestrain is related to work occupation)

Question 30

What does it mean when you get a P value of 0.32 in a fishers test

Answer 30

Cannot reject the null hypothesis - no difference between the categories

Question 31

What is the difference between the SEM and SD

Answer 31

SEM measures how far away the sample mean is from the true population mean SD measures scatter of data, or dispersion of individual data plots from the sample mean

Question 32

How is SEM claculated

Answer 32

SEM = SD / √n

Question 33

What type of data would we use a unpaired T test for

Answer 33

2 groups - unpaired, paramentric data

Question 34

What type of data would we use a paired T test for

Answer 34

2 groups - paired data, parametric

Question 35

What type of data would we use a Man-Witney Test for

Answer 35

2 groups - independant, non-parametric data

Question 36

What type of data would we use a oneway ANOVA for

Answer 36

3+ groups - independant, parametric data

Question 37

What type of data would we use a repated measured ANOVA for

Answer 37

3+ groups - related, parametric data