Week 6

Question 1

What is cognitive bias?

Answer 1

Ways of thinking that predispose one to favour a certain viewpoint over others

Question 2

What is confirmation bias?

Answer 2

Tendency to search for or interpret information in a way that confirms one’s preconceptions, while ignoring information that does not support the preconceptions

Question 3

What is selection bias?

Answer 3

Distortion of evidence or data that arises from the way that the data is collected or the way that samples are selected to study

Question 4

What is survivorship bias?

Answer 4

Survivorship bias is a type of selection bias that ignores the unsuccessful outcomes of a selection process

Question 5

What is publication bias?

Answer 5

Scientific journal editors and publishers more likely to publish studies with positive results over those with negative results

Question 6

Levels of measurement

Answer 6

Nominal scale
Ordinal scale
Interval scale
Ratio scale

Question 7

Nominal scale

Answer 7

simplest scale of measurement

variables which have no numerical value

variables which have catagories

examples: Gender, race, marital status

Question 8

Ordinal scale

Answer 8

variables are in categories, but with underlying order to their values

rank order categories from highest to lowest

intervals may not be equal

examples: cancer stages, pain ratings

Question 9

Interval scale

Answer 9

Where there is an order and the difference between two values is meaningful

The difference between any two values can be calculated by subtraction

Cannot multiply and divide values because there is no absolute zero

Example: Temperature -0 degrees doesn’t mean there is no temperature

Question 10

Ratio scale

Answer 10

Quantitative data with true zero

Can add, subtract, multiply and divide

Examples: Age, body weight, blood pressure

Question 11

Why is distribution important?

Answer 11

Determines which measure of central tendency to use (e.g. mean)

Determines which measure of variability to use (e.g. standard deviation)

Determines further statistical analysis

Question 12

Parametric

Answer 12

Assumes normal distribution

Question 13

Non-parametric

Answer 13

Non-normal distribution

Question 14

Indicators of central tendency

Answer 14

Mean - average

Median - middle score

Mode - most frequently occurring

Question 15

Choosing measures of average

Answer 15

Mode - not used very often generally avoid

Median - Use when the data is not normally distributed

Mean - Use when data is normally distributed

Question 16

What is variance?

Answer 16

Variance is a measure of how scattered around the average value one finds the measured values of a variable

Small variance means that measured values are on average, closer to the mean of the sample

Large variance means that measured values vary widely from the mean

Question 17

Measures of spread

Answer 17

Range

Interquartile range

Standard deviation

Question 18

What is range?

Answer 18

Largest observation minus the smaller observation

Question 19

What is interquartile range?

Answer 19

Upper quartile minus the lower quartile

Question 20

What is standard deviation?

Answer 20

Measures the average amount by which all the values deviate from the mean

Square root of the variance

Question 21

How is variance reported?

Answer 21

Error bars

Question 22

When to use standard deviation?

Answer 22

Used when the data is normally distributed