Univariate Data
One Variable
Qualitative Data
Categorical
Quantitative Data
Numerical
Discrete
Counted data; Specific values
Continuous
Measurable data
A population
Whole group
Sample
A small group chosen from the population
Simple Random Sampling
Selecting a sample completely at random
Systematic Sampling
Selecting a sample at a regular interval
Convenience Sampling
Getting data by selecting an easy to reach population
A biased sample
sample that does not represent diversity of population
Quota sampling
setting certain quotas for your sample
Stratified Sampling
selecting random sample where numbers in certain categories are proportional to numbers in their population
Percentile
Score below which a certain percentage of data lies
Lower quartile; 25th percentile
(n+1)/4
Median
(n+1)/2
Upper quartile; 75th percentile
(3(n+1))/4