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

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

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

HAWKES LEARNING SYSTEMS math courseware specialists Introduction to Statistics 1.3 Process of a Statistical Study Observational Study or Experimental Study? 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.

Ask, “How will the data be gathered?” Very Important: HAWKES LEARNING SYSTEMS math courseware specialists Introduction to Statistics 1.3 Process of a Statistical Study Observational Studies: 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.

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

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

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

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

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

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

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

HAWKES LEARNING SYSTEMS math courseware specialists Introduction to Statistics 1.3 Process of a Statistical Study Identify the sampling method: 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 12th 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

HAWKES LEARNING SYSTEMS math courseware specialists Introduction to Statistics 1.3 Process of a Statistical Study Identify the sampling method: 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

Questions not Part of This Chapter HAWKES LEARNING SYSTEMS math courseware specialists Introduction to Statistics 1.3 Process of a Statistical Study Questions not Part of This Chapter Don’t answer questions about: Meta Analysis Case Study Single-Masked Double-Masked

DATA WILL NOT BE CREATED !!!!!!!

MATH CLASSES ARE STRATAS, THE SAME NUMBER OF SUBJECTS ARE CHOSE FROM EACH STRATA.

EACH COUNTY IS A CLUSTER THAT IS SIMILAR TO THE POPULATION, AND THE WHOLE CLUSTERS (ALL THE MEMBERS) ARE CHOSEN AT RANDOM.

EVERY MEMBER OF THE POPULATION (ALL INSTRUCTORS) IS INCLUDED TO FIND THE AVERAGE SALARY.