The what and why of statistics

Question 1

What’s a statistic?

Answer 1

a numerical value that characterises the sample or population from which it was derived

Question 2

What’s statistical inference?

Answer 2

the theory, methods and practice of forming judgements about the parameters of a population and the reliability of statistical relationship, typically on the basis of random sampling

Question 3

What is empirical research?

Answer 3

• research based on info that can be verified by using our direct experience
• to answer research questions we can’t rely on reasoning or speculation

Question 4

What’s a hypothesis?

Answer 4

• derived from theory
• specific and exact statement about the relationship btw variables
• stated in terms of variables

Question 5

What’s a variable?

Answer 5

• any trait that can change values from case to case
• 2 types: dependent (effects/outcomes) and independent (causes)

Question 6

What’s the difference btw a population and a sample?

Answer 6

• population: collection of all possible cases of interest
• sample: carefully chosen subset of a population; used for study and analysis

Question 7

What are descriptive stats?

Answer 7

procedures that help us organize and describe data collected from either a sample or a population

Question 8

What are inferential stats?

Answer 8

procedures used to reach conclusions about a population from data collected from a sample

Question 9

What are the 3 levels of measurement for a variable?

Answer 9

• Nominal
• Ordinal
• Interval-ratio

Question 10

What are nominal levels of measurements?

Answer 10

• scores or categories that are non-numerical
• lowest level of measurement available
• only relative sizes of categories can be compared
  eg. gender, race. religion

Question 11

What are ordinal levels of measurement?

Answer 11

• scores or categories that can be ranked from high to low
• categories can be described as more or less with respect to each other
• we don’t know the distance from one score or category to the next
  eg. social class, Likert scales

Question 12

What are interval-ratio levels of measurement?

Answer 12

• measured as numbers
• scores can be ranked from high to low
• we can quantify distance btw different scores
  eg. income (in $), number of siblings, years of education