Materials developed by K. Watkins, J. LaMondia and C. Brakewood Data Collection With Surveys Unit 2: Describing Transit Systems with Data
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Outline Types of surveys Methods of sampling Survey content Survey instruments Data collection plan
Materials developed by K. Watkins, J. LaMondia and C. Brakewood TYPES OF SURVEYS Last time we discussed the type of information we collect. Now, let’s discuss how we go about collected detailed survey data.
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Types of Surveys Longitudinal survey – Over time Cross-sectional survey – Single point in time
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Survey Modes 1.On-board/Intercept 2.Telephone 3.Mail 4.Web-based 5.Smartphones (emerging)
Materials developed by K. Watkins, J. LaMondia and C. Brakewood On-Board & Intercept Surveys Overview Conducted on-board vehicles, in stations or at stops Target (study) population is current riders Very common: 96% of transit agencies conducted on-board surveys between * Pros & Cons + Easy to administer + Inexpensive + Relatively high response rates (33%-67%*) - Constraint of trip time on length of survey instrument (mail-back option) - Non-riders excluded
Materials developed by K. Watkins, J. LaMondia and C. Brakewood On-Board Survey Example
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Telephone Survey Overview Sampling frame is the household Often use Random Digit Dialing (RDD) Most common in cities with high use of transit – 71% of transit agencies conducted telephone surveys between * Pros & Cons + Riders and non-riders + Medium to long survey instruments + Good response rates - Interviewer training (Computer Aided Telephone Interviewing, or CATI, can help) - Respondent needs a (local) telephone
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Mail Survey Overview Sampling frame is the household Somewhat common – 38% of transit agencies conducted mail surveys* Pros & Cons + Riders and non-riders + Longer survey instruments + Easy to administer + Eliminates interviewer bias - Response rates can be very low; typically below 20%* - Usually not used for origin- destination surveys
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Web Survey Overview Sampling frame is riders (usually) Increasingly common – 44% of transit agencies conducted mail surveys between * Pros & Cons + Very inexpensive + Very easy to administer + Longer survey instruments + Eliminates interviewer bias + Data already coded - Respondent needs to have internet - Difficult to achieve random sample
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Smartphone Survey Overview Native smartphone applications can be used for travel surveys Geocoded travel information supplemented with survey questions Still in research & development – Some state DOTs; limited (if any) use in transit Pros & Cons + Geocoded travel information + Longer survey instruments + Relatively easy to administer + Data already coded - Respondent needs to have a smartphone - Difficult to achieve random sample - Privacy concerns
Materials developed by K. Watkins, J. LaMondia and C. Brakewood METHODS OF SAMPLING
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Methods of Sampling Simple Random Sampling Systematic Sampling – every n th unit selected Stratified Sampling – divide the population into homogenous groups (e.g. areas of the city) Cluster Sampling – natural groups, sample within groups Probability Proportionate to Size – selection probability proportional to size
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Sample Size Determination Depends on the population size (e.g. number of riders) and the level of precision desired Increase sample size increase costs Example for Simple Random Sampling
Materials developed by K. Watkins, J. LaMondia and C. Brakewood SURVEY CONTENT What is commonly included in transit surveys?
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Research Goals & Content Origin & Destination Surveys – “This trip”: Origin, destination, purpose, access mode, egress mode, etc. General Travel Behavior – Frequency of travel, how long using transit, alternative modes Demographics – Gender, age, race, driver’s license, HH income, HH size, employment status Satisfaction – Attributes of service: timely service, speed of service, cleanliness, comfort, safety, crowing, information Other – Fare payment, new technologies, communications, etc.
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Translating Research into Survey Questions
Materials developed by K. Watkins, J. LaMondia and C. Brakewood SURVEY INSTRUMENT How to write a good survey
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Types of Questions Closed-Ended – Dichotomous (2 answers, e.g. Yes/No) – Nominal (Categorical) – Ordinal (a.k.a. Likert, Ranking) – Filter/Contingency (Qualified) Partially-Closed – Last answer is “Other______” Open-Ended
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Do’s and Don’ts Questions should be: – Concise (multiple choice) – Understandable – Useful – Exhaustive Questions should NOT be: – Double-barreled – Double negative – Technical jargon – Long-winded – Redundant – Obtrusive or embarrassing
Materials developed by K. Watkins, J. LaMondia and C. Brakewood IN-CLASS EXERCISE Now, its time for you to practice
Materials developed by K. Watkins, J. LaMondia and C. Brakewood DATA COLLECTION PLAN Putting it all together in order to create a…
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Creating a Data Collection Plan 1.Determine research goals 2.Select survey mode & sampling methodology 3.Determine necessary sample size 4.Create detailed sampling plan 5.Draft questionnaire 6.Pre-test the questionnaire 7.Conduct staff training 8.Distribute survey & revise sampling plan 9.Code/process data & error check
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Other Considerations Language – English & Spanish Special groups – Those who cannot read/write Longitudinal comparisons – Consistency of questions with prior transit surveys
Materials developed by K. Watkins, J. LaMondia and C. Brakewood CHICAGO TRANSIT AUTHORITY What does a (good) transit survey look like?
Materials developed by K. Watkins, J. LaMondia and C. Brakewood 2003 Chicago Transit Authority Customer Satisfaction Survey Objective: Comprehensive review of customer satisfaction conducted every 2 to 3 years Content Included: – General travel behavior (modes, trip purpose) – Satisfaction with service delivery attributes – Loyalty towards CTA – Technology use (internet access, CTA website) – Fare payment – Demographics
Materials developed by K. Watkins, J. LaMondia and C. Brakewood CTA: Mode & Sampling Mode: Household Telephone survey – Random Digit Dialing – Computer Assist Stratified Sampling – Area of residence (N, S, NW, SW, W, Suburbs) – Mode (rail or bus) Sample Size – Minimum of 200 respondents per strata – Total of 2,577 responses
Materials developed by K. Watkins, J. LaMondia and C. Brakewood CTA: Questionnaire Question types – Mostly closed-ended questions (scales typically 5 points) – A few partially closed (other) & open ended questions Interview length – Average of 21.4 minutes to complete – Pre-tested to assure length Response rate – 64,986 telephone numbers attempted
Materials developed by K. Watkins, J. LaMondia and C. Brakewood CTA: Results Satisfaction with bus service: – Has improved terms of reliability, information services, and comfort, among other things. – Has decreased in regards to access to service, personal safety, and intramodal transferring (within CTA). Satisfaction with rail service: – Has improved or stay constant in terms of operator attributes (personnel), information sources, reliability and fare payment, among other things. – Has decreased in regards to access to service, intramodal travel, personal safety, and appearance.
Materials developed by K. Watkins, J. LaMondia and C. Brakewood CTA: Results
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Conclusion Surveys are a good way for agencies to know who their riders are and what they want. There are several survey types with varying costs, penetration and bias. They should be chosen to match their target. Surveys should be easy to understand and should encourage participants to complete them.
Materials developed by K. Watkins, J. LaMondia and C. Brakewood Reference Materials in this lecture were taken from: Schaller. “On-board and Intercept Transit Survey Techniques”. Transit Cooperative Research Program Synthesis 63, National Research Council, Washington, DC (2005). CTA, Customer Satisfaction Survey, 2003.