Module 3: Learning Objectives

Question 1

What is a variable?

What three pieces of information does it contain?

Answer 1

Any measurable characteristic of an observation unit (ex. number of tweets a person reads)

1) what it represents (long jump distance)
2) measurement unit (cm)
3) description of observation unit (student)

Question 2

What is data?

Answer 2

Value of variable you measure from observation unit.

Question 3

List 4 types of variables

Answer 3

1. Continuous numerical: decimals
2. Discrete numerical: integers
3. Ordinal categorical: ranked scale
4. Nominal categorical: no scale

Question 4

What is the difference between central tendency and dispersion

Answer 4

Central tendency: middle value (mean, counts, proportions)

Dispersion: variation (variance, range)

Question 5

Counts vs proportions

Answer 5

Counts: number of observation in sample that fall in category (#)

Proportions: the share of total sampling units (%) (must share total count)

Question 6

How to calculate

1) Mean
2) Variance
3) Standard deviation

Answer 6

1) sum all numbers / number of variables
2) 1. mean 2. for each number subtract mean and square result 3. find average of all of these
3) Square root of variance

Question 7

How to calculate

1) Quartiles

Answer 7

1. sort data from lowest to highest
2. find 2nd quartile (median) split data in half (if odd its middle value, if even its average of two middle values)
3. find 1st quartile by using the lower half middle (same as #2) (include 2nd quartile is observations is odd)
4. find 3rd by step 3 but on upper half
5. find IQR (Q3-Q1)

Question 8

What is effect size?

Answer 8

Tells us if change in response variables is meaningful, calculated as difference or ratio