Download presentation

1
**Chapter 2 Samples and Populations**

Sample vs. Population Design Methods Construction Errors

2
**Population/Target Population**

Sample vs. Population Population – the totality of subjects under consideration Target Population – consists of all subjects considered in the study Sample – a portion or a subset of the population for data collection and analysis Population/Target Population Sample

3
**Young-adults and older**

Sample vs. Population Population Target Population Sample Kalamazoo Young-adults and older House -holds

4
**Census vs. Sample Survey**

Census – collection of data using all subjects in the population Sample Survey – collection of data from a representative sample of the population Population/ Target Population Sample Note: Random Samples should be representative of the population

5
**Study Design or Protocol Design**

Steps involved in solving problems How do I solve this problem? ? ? Study design is done prior to data collection. It involves methods in data collection, analysis of the data and conclusions to be made.

6
**Probability vs. Non-Probability Sampling**

Probability Sampling – subjects are chosen by chance Non-probability Sampling – can be used for informal and less scientific studies Note: Non-probability sampling tend to be less representative of the target population

7
**Methods in Probability Sampling**

Simple Random Sampling (SRS) – samples are randomly selected from the population K-in-1 Systematic Sampling – Every kth subject is chosen Stratified Random Sampling – population is divided into subgroups called strata and SRS chosen from each strata Cluster sampling – population is divided into subgroups called clusters and clusters are randomly chosen as samples.

8
**Example: Household Expenditures in Michigan**

Target Population : Households in Michigan Simple Random Sampling – randomly selecting the sample from a list of households Systematic Sampling – every 10th household Stratified Sampling – take samples from each county Cluster Sampling – selecting counties in Michigan

9
**Factors to be considered in a Survey**

Money Time Content/Information

10
**Types of Surveys Type of Survey Advantages Disadvantages**

Face-to-face Interview Explain questions, explore issues, make observations, use visual aids Expensive, need interviewer training - at home or work Accuracy, better sampling Expensive - in public areas Cheaper, more people in less time Less representative sample Telephone Interview Accurate, cheap No personal observation Written Questionnaire Cheapest per respondent Bias from low response rate - by mail Allows anonymity Slow - by Cheaper, quicker results - web survey Quicker data processing Need computing expertise

11
**Construction of Questionnaire**

Is the question understandable? Are you gathering knowledge or attitude? Are the questions loaded? Do the questions ask for sensitive information? Note: An accurate answer leads to a good study and it starts from asking important questions correctly.

12
Types of Survey Errors Coverage errors – sampling frame excludes some segments of the target population Non-response errors – can cause bias in survey results Measurement errors – occurs when respondents answer ‘incorrectly’

Similar presentations

Presentation is loading. Please wait....

OK

AP Statistics!!! Test Review 2013.

AP Statistics!!! Test Review 2013.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on business etiquettes training courses Small ppt on save water Ppt on oxygen cycle and ozone layer Ppt on credit policy and procedure Ppt on kingdom monera example Ppt on collections in c# Ppt on articles a an the Convert pdf ppt to ppt online training Knowledge based view ppt on android Ppt on 60 years of indian parliament attack