Lesson#1 Gathering Data May 26, 2011

SECTION A: DATA Population: The entire group of items or individuals being considered Census: a survey of the entire population Sample: a small group of item of individuals chose to represent the entire population Primary Source Data: data collected directly by the person or group who will use the information. Examples include: personal and telephone interviews, surveys, observations, measurements, product testing. Secondary Source Data: data that have already been collected and are made available to the public. Examples include: Statistics Canada, the media, the internet, publications from polling firms.

SECTION B: SELECTING A SAMPLE Sample selection is an important part of survey design. If a sample size is too small or if the individuals or items chosen are not truly representative of the population, then the sample may be biased and will lead to results that are not valid. Some types of samples that you should know: Simple Random Sample: all members of the population have an equal chance of being selected. Stratified Random Sample: all members of different segments or subsections of the population have an equal chance of being selected

Cluster Sample: every member of a randomly chosen section of the population is chosen Systematic sample: every nth member of the population is selected Convenience Sample: members are selected based on convenience Judgement Sample: the person doing the sampling uses her/his judgement to select a representative simple Self-Selected or Voluntary Sample: only interested member of the population participate

Survey design: When you are designing survey questions, consider the purpose of or reason for the question. Ask yourself: What are you looking to find out by asking that particular question? Is the question clear or does it leave room for interpretation? Is the question worded in such a way so as to influence the participant to respond in a certain way?

OPEN Question: a question where the participant provides a his/her own words CLOSED Question: a question where the participant selects a response from a list of choices See examples on handout Create 5 open questions and 5 closed questions. Trade with another member of the class and have them answer your questions. They will decide if Your questions are worded clearly The questions are biased The questions could be improved in any way