STAT 1222 Test 1

Population

The group of all persons, objects, or things that you want to study; the target audience (ex. Students in the classroom)

Parameter

A numerical characteristic of the population, usually the average. ex. average income, average household, etc (ex. mean number of hours everyone has been awake)

Sample

A small subset of the population that we select to study (ex. group 9)

Statistic

A numerical characteristic of the sample (ex. the mean number of hours group 9 has been awake)

Variable

The numerical value everyone in the population has (ex. age, business income, and expenses)

Data

The list of numbers from those in your sample (ex. amount of money, pulse rate)

Nominal Data

Categorical data that cannot be meaningfully ordered (ex. red, blue, green)

Ordinal Data

Categorical data that can be meaningfully ordered (ex. A+, A, C, F)

Interval Data

Numerical data that has no “true” zero and ratios have no meaning (ex. time, calendars, temperature (excluding Kelvin))

Ratio Data

Numerical data that has a “true” zero and ratios have meaning (ex. height, distance, percentages, age)

Simple Random Sampling

Each member of a population has an equal chance of being selected for the sample

Stratified Sampling

Population is divided into groups first called strata, and take a sample from each

Cluster Sampling

Divide the population into clusters, then randomly select a cluster

Systematic Sampling

Randomly select a starting point, then select every nth member of the population

Convenience Sampling

Using research/results that are readily available, or easiest to obtain

Voluntary Response Sampling

Sample chooses to respond to the survey themselves

Qualitative Data

Data that cannot be counted, measured or easily expressed using numbers

Quantitative Discrete Data

A type of quantitative data that can take only fixed values, always numerical and data that can be counted, but not measured (ex. the number of people in a class or test questions answered correctly)

Quantitative Continuous Data

A type of quantitative data set representing a scale of measurement that can consist of numbers other than whole numbers, like decimals and fractions (ex. height, weight, length, temperature)

Outlier

An observation that is radically different from the rest

Skewed left

(often) mean < median

Skewed right

(often) mean > median

Symmetrical graph

mean = median

Mean

the average of a data set

Median

The middle number in a sorted list of numbers

Mode

The value that appears most frequently in a data set

Population Mean

μ

Sample Mean

x̄

Sample Standard Deviation

s.

Standard Deviation

The measure of the amount of variation of a random variable expected about its mean

Variance

The measurement of the spread between numbers in a data set

Population Variance

σ²

Sample Variance

s²

Z-Score

measures exactly how many standard deviations above or below the mean a data point is