Data Collection Data Collection Definitions Level of Measurement Time Series and Cross-sectional Data Sampling Concepts Sampling Methods Data Sources Survey Research Chapter 22 Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin

Data: Singular or Plural? Data: Singular or Plural? Subjects, Variables, Data Sets Datadata setWe will refer to Data as plural and data set as a particular collection of data as a whole. Observation Observation – each data value. Subject Subject (or individual) – an item for study (e.g., an employee in your company). Variable Variable – a characteristic about the subject or individual (e.g., employee’s income). 2-2

Data Definitions Data Definitions Categorical or Qualitative – data values which are non-numeric Numerical or quantitative – data values which are numeric Data Coding – done to simplify the data when the exact data magnitude is of little interest Binary Data – data values with only two values, indicating the presence (1) or the absence (0) of a characteristic of interest Discrete Data – data values which arise from counting Continuous Data – numerical values which lie within an interval 2-3

Level of Measurement Level of Measurement Levels of Measurement Level of Measurement CharacteristicsExample NominalCategories only (blue, brown, green, hazel) Eye color (blue, brown, green, hazel) OrdinalRank has meaningBond ratings (Aaa, Aab, C, D, F, etc.) IntervalDistance has meaningTemperature (57 o Celsius) RatioMeaningful zero existsAccounts payable ($21.7 million) 2-4

Level of Measurement Level of Measurement Likert Scales Likert Scales A special case of interval data frequently used in survey research. The coarseness of a Likert scale refers to the number of scale points (typically 5 or 7). “College-bound high school students should be required to study a foreign language.” (check one)  StronglyAgreeSomewhatAgree Neither Agree Nor Disagree SomewhatDisagreeStronglyDisagree 2-5

Time Series vs. Cross Sectional Data Time Series vs. Cross Sectional Data Time Series data – data values observed over time Cross Sectional Data – values observed at the same point in time 2-6

Sampling Concepts Sampling Concepts sampleA sample involves looking only at some items selected from the population. censusA census is an examination of all items in a defined population. target populationThe target population is the population we are interested in (e.g., U.S. gasoline prices). sampling frameThe sampling frame is the group from which we take the sample (e.g., 115,000 stations). 2-7

Sampling Concepts Sampling Concepts StatisticsStatistics are computed from a sample of n items, chosen from a population of N items. parametersStatistics can be used as estimates of parameters found in the population. Symbols are used to represent population parameters and sample statistics. 2-8

Sampling Methods Sampling Methods Probability Samples Simple Random Sample Use random numbers to select items from a list (e.g., VISA cardholders). Systematic Sample Select every kth item from a list or sequence (e.g., restaurant customers). Stratified Sample Select randomly within defined strata (e.g., by age, occupation, gender). Cluster Sample Like stratified sampling except strata are geographical areas (e.g., zip codes). 2-9

Sampling Methods Sampling Methods Non-probability Samples Judgment Sample Use expert knowledge to choose “typical” items (e.g., which employees to interview). Convenience Sample Use a sample that happens to be available (e.g., ask co-worker opinions at lunch). Focus Groups In-depth dialog with a representative panel of individuals (e.g. iPod users). 2-10

Sampling Methods Sampling Methods With or Without Replacement With or Without Replacement with replacementIf we allow duplicates when sampling, then we are sampling with replacement. Duplicates are unlikely when n is much smaller than N. without replacementIf we do not allow duplicates when sampling, then we are sampling without replacement. 2-11

Data Sources Data Sources Many excellent sources are widely available. The following table summarize a few of them. 2-12

Step 1: State the goals of the research. Step 1: State the goals of the research. Step 2: Develop the budget (time, money, staff). Step 2: Develop the budget (time, money, staff). Step 3: Create a research design (target population, frame, sample size). Step 3: Create a research design (target population, frame, sample size). Step 4: Choose a survey type and method of administration (mail, telephone, interviews, web, Step 4: Choose a survey type and method of administration (mail, telephone, interviews, web, direct observations. direct observations. Basic Steps of Survey Research Basic Steps of Survey Research Survey Research Survey Research 2-13

Step 5: Design a data collection instrument (questionnaire). Step 5: Design a data collection instrument (questionnaire). Step 6: Pretest the survey instrument and revise as needed. Step 6: Pretest the survey instrument and revise as needed. Step 7: Administer the survey (follow up if needed). Step 7: Administer the survey (follow up if needed). Step 8: Code the data and analyze it. Step 8: Code the data and analyze it. Basic Steps of Survey Research Basic Steps of Survey Research Survey Research Survey Research 2-14

2-15 Survey Guidelines Survey Guidelines Survey Research Survey Research Planning: What is the purpose of the survey? Consider staff expertise, needed skills, degree of precision, budget. Design: Invest time and money in designing the survey. Use books and references to avoid unnecessary errors. Design: Invest time and money in designing the survey. Use books and references to avoid unnecessary errors. Quality: Take care in preparing a quality survey so that people will take you seriously. Quality: Take care in preparing a quality survey so that people will take you seriously.

2-16 Survey Research Survey Guidelines Pilot Test: Pretest on friends or co-workers to make sure the survey is clear. Pilot Test: Pretest on friends or co-workers to make sure the survey is clear. Buy-in: Improve response rates by stating the purpose of the survey, offering a token of appreciation or paving the way with endorsements. Buy-in: Improve response rates by stating the purpose of the survey, offering a token of appreciation or paving the way with endorsements. Expertise: Work with a consultant early on.

Questionnaire Design Questionnaire Design Instruct on how to submit the completed survey. Use a lot of white space in layout. Begin with short, clear instructions. State the survey purpose. Assure anonymity. Survey Research Survey Research 2-17

Questionnaire Design Questionnaire Design Break survey into naturally occurring sections. Let respondents bypass sections that are not applicable (e.g., “if you answered no to question 7, skip directly to Question 15”). Pretest and revise as needed. Keep as short as possible. Survey Research Survey Research 2-18