Stats Test 1

Parameter

Population

Statistics

Sample

Stratified sample

sampling method that divides the population into distinct groups before sampling.

convince sample

sampling method that relies on the judgment of the researcher to select participants, often resulting in a non-random sample. Just asking anyone.

voluntary response

sampling method where participants self-select to be included, often leading to biased results.

cluster sampling

A sampling method that divides the population into clusters, usually based on geography or other naturally occurring groups, and then randomly selects entire clusters for analysis.

simple random sampling

A sampling method where each member of the population has an equal chance of being selected. This can be achieved using random number generators or drawing names from a hat.

systematic sampling

A method where participants are selected at regular intervals from a list. For example, if you want to pick every 10th person from a queue, you would start at a random point and then continue selecting every 10th person from there.

Qualitative data

Classifies individuals into categories

Quantitative

Numerical data

Nominal

Does not have a natural ordering (can be categorized but not ranked)

Ordinal

Has a natural ordering (rankings or scalings)

Discrete data

refers to specific and distinct values or observations that can be counted. Unlike

Continuous data

numerical variables that can assume any value within a specified range. They can take on an infinite number of values between two endpoints. The values they assume do not have fixed intervals and can be represented with any degree of precision via fractions or decimal points.

Observational study

a research method where data is collected by observing subjects in their natural environment without intervention or manipulation.

Double blind experiment

a research design where neither the participants nor the researchers know who receives the treatment or a placebo. It eliminates participant bias

Randomized experiment

a study design where participants or subjects are randomly assigned to a treatment group or a control group. This process neutralizes confounding variables, ensures baseline comparability, and allows researchers to attribute outcome differences directly to the intervention (causation) rather than selection bias

Relative frequency formula

Frequency of the event (or category)

Total number of trials or items

Relative frequency to pie chart (in degrees)

Relative Frequency x 360

mean symbol

x̄

Median symbol

Med

Mode

Most reoccurring number

resistant measure

value is not significantly affected by extreme data points or "outliers".

Midpoint

lower limit for a class +lower limit of next class

2

skewed to the left

Mean is less than the median

skewed to the right

mean is greater than the median

sample variance

s²

Sample standard deviation

Sx

IQR

Q3-Q1

Mean symbol

μ

Standard deviation symbol

σ