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Quantitative Data

Data that can be measured and represented as numbers.

Qualitative Data

Descriptive data that cannot be measured or reduced to numbers.

Discrete Data

Data that can only take whole number values.

Continuous Data

Data that can take any value within a range, including decimals.

Sampling Methods

Techniques used to select individuals from a population to participate in a study.

Random Sampling

A sampling method that gives each individual an equal chance of being selected.

Systematic Sampling

A method where you select every nth individual from a list.

Stratified Sampling

A method that ensures representation from all subgroups within a population.

Cluster Sampling

A sampling method where entire groups are selected randomly.

Response Bias

Bias that occurs when the way questions are asked influences the responses.

Nonresponse Bias

Bias that occurs when certain groups do not participate in the survey.

Selection Bias

Bias that occurs when the sample does not accurately reflect the population.

Mean

The average of a set of values, sensitive to outliers.

Median

The middle value in a data set, useful for skewed data.

Mode

The most frequently occurring value in a data set.

Standard Deviation (σ)

A measure of the spread of data points around the mean.

Normal Distribution

A probability distribution that is symmetric and bell-shaped.

Empirical Rule

A guideline stating that for a normal distribution, about 68% of data falls within one standard deviation, 95% within two, and 99.7% within three.

z-Score

A measure of how many standard deviations a value is from the mean.

Correlation Coefficient (r)

A numerical measure of the strength and direction of a linear relationship between two variables.

Regression Line

A line that best fits the data points in a scatter plot, used to predict values.

Residuals

The difference between observed values and predicted values.

Simple Probability

The likelihood of a single event occurring, calculated as favorable outcomes divided by total outcomes.

Complement

The probability that an event does not occur.

Mutually Exclusive Events

Events that cannot occur at the same time.

Independent Events

Events where the occurrence of one does not affect the occurrence of the other.

Conditional Probability

The probability of an event occurring given that another event has already occurred.

Binomial Probability

Probability related to a scenario with two possible outcomes over multiple trials.

Expected Value (E(X))

The predicted average outcome of a random variable.

Margin of Error (MOE)

The amount of random sampling error in a survey's results.

Confidence Interval

A range of values used to estimate the true parameter in the population, with a specific level of confidence.