Materials developed by K. Watkins, J. LaMondia and C. Brakewood Data Collection With Surveys Unit 2:...

Materials developed by K. Watkins, J. LaMondia and C. Brakewood

Data Collection With Surveys

Unit 2: Describing Transit Systems with Data


Outline

• Types of surveys

• Methods of sampling

• Survey content

• Survey instruments

• Data collection plan


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.


Types of Surveys

• Longitudinal survey– Over time

• Cross-sectional survey – Single point in time


Survey Modes

1. On-board/Intercept 2. Telephone 3. Mail 4. Web-based 5. Smartphones (emerging)


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 2002-2004*

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


On-Board Survey Example


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 2002-2004*

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


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


Web Survey

Overview

• Sampling frame is riders (usually)

• Increasingly common– 44% of transit agencies

conducted mail surveys between 2002-2004*

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


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


METHODS OF SAMPLING


Methods of Sampling

• Simple Random Sampling• Systematic Sampling– every nth 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


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


SURVEY CONTENTWhat is commonly included in transit surveys?


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.


Translating Research into Survey Questions


SURVEY INSTRUMENTHow to write a good survey


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


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


IN-CLASS EXERCISENow, its time for you to practice


DATA COLLECTION PLANPutting it all together in order to create a…


Creating a Data Collection Plan

1. Determine research goals 2. Select survey mode & sampling methodology3. Determine necessary sample size4. Create detailed sampling plan5. Draft questionnaire6. Pre-test the questionnaire7. Conduct staff training8. Distribute survey & revise sampling plan 9. Code/process data & error check


Other Considerations

• Language – English & Spanish

• Special groups – Those who cannot read/write

• Longitudinal comparisons– Consistency of questions with prior transit surveys


CHICAGO TRANSIT AUTHORITY

What does a (good) transit survey look like?


2003 Chicago Transit AuthorityCustomer 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


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


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


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.


CTA: Results


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.


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.

Materials developed by K. Watkins, J. LaMondia and C. Brakewood Data Collection With Surveys Unit 2:...

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