Mehdi Elharti

What are Quantitative Methods? involves the gathering, organization, and

mathematical analysis of information

enables decision makers to characterize a given entity/population quantitatively, compare it to another or others, and arrive at meaningful insights (inference)

Why Quantitative Methods?

Forecasting sales/revenues

Estimate competitive threats

Examining consumer attitudes

Evaluating advertising effectiveness

Establishing pricing policy

Appraise quality control

Data Information Knowledge Wisdom

Obtaining Data

Primary data: conduct your own research project

Secondary data: obtain data from

Market research firms

Advertising agencies

Trade associations

Professional associations

Governmental agencies

International agencies

Professional journals and publications …

Primary data: Sampling Probability sampling methods: every unit in the population

has a chance (greater than zero) of being selected in the sample. Simple random sampling

Stratified sampling

Cluster sampling

Systematic sampling

Nonprobability sampling methods: some elements of the population have no chance of selection (out of coverage) Convenience

Judgemental

Snowball …

Simple Random Sampling Every element of the population has an equal chance of

being selected

Used when the population is relatively homogeneous and a sample frame is available

Stratified Sampling The population is first separated into mutually

exclusive, homogeneous segments (strata)

A simple random sample is selected from each strata

the samples selected from the various strata are then combined into a single sample.

Stratified sampling is used when:

the population is heterogeneous according to a particular characteristic

the characteristic upon which the population is stratified is strongly correlated with the variable we seek to obtain

Cluster sampling Cluster sampling is when elements of the population

are randomly selected in naturally occurring groupings (clusters).

It is used when:

it is impossible or impractical to create a sampling frame of a population

the target population is widely dispersed geographically, making data collection costs relatively high

Representing Data There is a multitude of graphs to represent your data:

Line graphs

Bar chart (vertical/horizontal)

Pie Chart

Scatter diagram

The trick is to know which one to use

Rainfall and average wheat yield

Department

StoreTotal Sales by DepartmentA B C

Clothing 254 68 152 474

Furniture 129 287 25 441

Electronics 74 310 245 629

Total sales by Store 457 665 422 1544

Sales data of a department chain in 2005

Shoe size and height