1. 16th TRB Planning Applications Conference - 2017
A Utility-Theory Consistent Model of Activity Frequency, Purpose, and, Duration Choices
Rajesh Paleti
Chaitanya Paleti
16th TRB Planning Applications Conference
11/28/2018

2. Activity Based Modeling (ABM)
ABM Models – Two major components
Planning Stage – frequency, purpose, duration
Scheduling Stage – Mode, destination, departure time
Work
Shopping
Discretionary
T1 Mins
T2 Mins
Tn Mins
Activity 1
Activity n
Activity 2
Three dimensions to the activity-travel choices that people make at the planning stage
out-of-home activity participation frequency,
activity purpose of the activity episodes, and
duration associated with each episode
11/28/2018
2017 TRB Planning Applications Conference

3. Past ABM Research & Applications
Work
Shopping
Discretionary
t1 Mins
t2 Mins
tn Mins
Activity 1
Activity n
Activity 2
Frequency
Activity Purpose
Duration
Count Data Models
Choice Models
Duration Models
Poisson’s Models; Negative Binomial Models
Multinomial Logistic (MNL) Models
Regression/
Hazard Duration Models
Consistent with Utility Theory
11/28/2018
2017 TRB Planning Applications Conference

4. 2017 TRB Planning Applications Conference
Limitations
Activity Frequency, Purpose, and, Duration choices are inter-related in nature
Models used to predict frequency and duration are not consistent with Random Utility Theory
11/28/2018
2017 TRB Planning Applications Conference

5. Current Study Objectives
Propose a new modeling framework - a single utility theory consistent model for all the dimensions of activity-time use decisions
Demonstrate that the joint model offers superior data fit and prediction accuracy than standard models
11/28/2018
2017 TRB Planning Applications Conference

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Virginia NHTS Data
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2017 TRB Planning Applications Conference

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Key Empirical Results
Higher auto ownership levels, higher income levels, regular internet use lead to more OH activity episodes
Presence of children 0 to 5 years, bachelor and higher educational attainment, older age (> 65 years) decrease # of OH activity episodes
Several socio-demographics including age, gender, household composition, income, educational attainment, presence of children, auto ownership impact activity purpose and duration
Higher expected utility from activity participation will result in more OH activity episodes
Statistical Fit Comparison
Log-likelihood ratio test and Bayesian Information Criterion (BIC) statistics demonstrate superior data fit in the joint model compared to independent count and MNL models
11/28/2018
2017 TRB Planning Applications Conference

8. 2017 TRB Planning Applications Conference
Next Steps
Validate the estimated models on 50% data retained for data validation
Predict using the models and compare with observed frequency, purpose, and duration choices
Compare the model performance with standard models
Test for traveler-specific unobserved factors that impact all activity purpose and duration choices  “unobserved heterogeneity”
11/28/2018
2017 TRB Planning Applications Conference

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Thank You!
For more information:
Rajesh Paleti
Chaitanya Paleti, P.E.
11/28/2018
2017 TRB Planning Applications Conference