stat ded

A statistic

is a numerical summary of a sample.

Descriptive statistics

is the organizing and summarizing of data through tables, graphs, and numerical Summaries

Statistics

is the science of collecting, organizing, summarizing, and analyzing information to draw conclusions or answer questions. It is also about providing a measure of confidence in any conclusions.

A sample

is a subset of the group of individuals that is being studied.

Inferential statistics

uses methods that take results from a sample and extends them to the population, and measures the reliability of the result.

An individual

is a person or object that is a member of the group being studied.

A parameter

is a numerical summary of a population.

A population

is the entire group of individuals to be studied.

A quantitative variable

provides numerical measures of individuals. The values of a quantitative variable can be added or subtracted, and provide meaningful results.

A qualitative variable

allows for classification of individuals based on some attribute or characteristic.

A variable

is the characteristic of the individuals within the population.

Data

is information that describes characteristics of an individual.

A discrete variable

has either a finite number of possible values or countable number of possible values.The values of these variables typically result from counting.

A continuous variable

has an infinite number of possible values that are not countable. The values of these variables typically result from measurement.

Ratio

• data have ordered categories with equal differences and a true zero point, allowing for meaningful ratios (e.g., height, weight, age).

Nominal

• data are categories with no order (e.g., colors, types of cars).

• Ordinal

• data have categories with a meaningful order, but the differences between categories are not necessarily equal or quantifiable (e.g., rankings like
  "good," "better," "best").(Student grading )

Interval

• data have ordered categories where the differences between values are equal and meaningful, but there is no true zero point (e.g., temperature in Celsius or Fahrenheit).

Systematic

Select every k-th individual from a list after a random start.

Stratified

Population divided into groups (strata), then random sample taken from each group.

Convenience

Select individuals who are easiest to reach.

Simple random

Every individual has an equal chance of being selected.

Cluster

Population divided into groups (clusters), then entire clusters are randomly selected.

What does it mean when an observational study is retrospective?

1. A retrospective study requires that individuals look back in time or require the researcher to look at existing records.

What does it mean when an observational study is prospective?

1. A prospective study collects the data over time.

A frequency distribution lists the ___ of occurrences of each category of data.

Number

A relative frequency distribution lists the ____ of occurrences of each category of data.

Proportion

The____ is the difference between consecutive lower class limits

Class width