Introduction to StatisticsIntroduction to Statistics

BUSA 2100, Sect. 1.0, 1.2 - 1.5

Dr. Moore

Definition of StatisticsDefinition of Statistics

Many people think of statistics as large amounts of numerical data, e.g. stock prices, sports statistics.

Definition: The academic discipline of statistics is the study of how data are collected, analyzed, summarized, presented, and interpreted.

Why Study Statistics?Why Study Statistics?

1.Statistics are widely used in bus-iness. Usage continues to increase as the business world becomes larger, more complex, and more quantitative.

2.Statistics provide data and tools for better quality decision making.

Why Study Stat? / DefinitionsWhy Study Stat? / Definitions

3. Decisions made using quantitative data tend to be more accurate, more objective, and more easily defended.

Definition: Data are facts and figures. Qualitative or categorical data: labels,

names, non-numeric descriptions, and numeric codes. (State examples.)

More About DataMore About Data

Quantitative data: always numeric; indicate how much or how many.

Where do data come from? We will consider 5 source categories.

1. Internal business records: personnel records, sales records, inventory records, financial statements

Sources of DataSources of Data

2. Internet: company web sites 3. Experimental studies: prescription drug

comparisons, agricultural plots 4. Governmental agencies: Dept. of Labor

(wages, employment rates); Census Bureau (populations, data about households).

5. Surveys: Questionnaires or interviews to obtain information about topics of interest.

Branches of StatisticsBranches of Statistics

The academic discipline of statistics can be divided into two major branches: descriptive and inferential statistics.

Descriptive statistics: Deals with summarizing and presenting data in a readable, easily understood form.

Ex.: Graphs, tables, charts, averages

Descriptive Stat. ExampleDescriptive Stat. Example Example: Daily high temperatures in

Atlanta for the past 10 years; N = 3,650.

Inferential StatisticsInferential Statistics

The amount of data has been greatly reduced and is much easier to under-stand.

Inferential statistics: Drawing conclusions about a population based on information from a sample.

Populations and SamplesPopulations and Samples

Population: Set of all items of interest in a particular study.

Sample: A subset (portion) of the population.

Examples of inferential statistics: Nielsen TV ratings surveys, political preference polls.