Section 1.3 The Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists Copyright © 2008 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved.

Collect Data Defines Population/ Variables Question Calculate Statistic Estimate Parameter Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

Observational Study – researcher observes data that already exists. Experiment – researcher seeks to create data to identify cause and effect relationships. Types of Studies: Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

A medical researcher wants to examine the effects of exercise on cardiovascular health. Experimental A recording company is interested in knowing the percentage of teenagers that download music off of the internet. Observational A chain of grocery stores wants to know how much the average family spends on produce each month. Observational Observational Study or Experimental Study? Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

Ask, “How will the data be gathered?” Very Important: It is essential that a representative sample is chosen out of the population. A good sampling frame is the first step to choosing a representative sample. The sampling frame is a list of members of the population. Observational Studies: Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

Census Random Sample Stratified Sample Cluster Sample Systematic Sample Convenience Sample Sampling Techniques: Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

Census: Every member of the population is included. Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

Random Sample: Every member has an equal chance of being selected. Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

Stratified Sample: The population is divided into subgroups called strata and the same number of subject are chosen from each strata. Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

Cluster Sample: The population is divided into subgroups, called clusters, that are similar to the population and whole clusters are chosen at random. Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

Systematic Sample: Selecting every n th member of the population. Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

Convenience Sample: The sample is convenient for the researcher to select. Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

Chosen at random, 200 rural and 200 urban persons age 65 or older were asked about their health and experience with prescription drugs. Stratified For quality assurance, every 12 th engine part is selected from an assembly line and tested for durability. Systematic A survey concerning the taste of a new soda flavor was performed at the local grocery store from 5:00 PM to 8:00 PM. Convenience Identify the sampling method: Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists

To determine how a particular political candidate was going to fare in an upcoming election, different counties in the state were randomly selected and every eligible voter in the randomly selected counties was surveyed. Cluster To determine who will win a $100,000 shopping spree at the local mall, the owner of the mall draws a name out of a box. Random Identify the sampling method: Introduction to Statistics 1.3 Process of a Statistical Study HAWKES LEARNING SYSTEMS math courseware specialists