Conflict and Interaction: a Structural Equations Analysis of Relationships between Time Allocation and Travel Behavior

Zhang Wenjia and Chai YanweiCollege of Urban and Environment, Peking University

Content

1. Introduction2. Research reviews3. Data4. Methodology5. Findings and interpretations6. Concluding discussion

2007/12/14

2

1. Introduction• Up until now, researches of individual time allocation

and travel behavior have played a dominant role in urban transportation studies; however there exist many cases in which intrapersonal conflict and intra-household interaction cannot be ignored, especially in developing China.

• Household and activity-travel behavior▫ Family demand (Chapin, 1974; MAGIC…)▫ Conflict between Family obligation and others (Gronlund,

2007…)▫ Intra-household interaction among household members

(Golob and McNally, 1997; Roehling and Bultman , 2002…)

2007/12/14

3

Questions• how does the activities of family and work

obligation directly affects other activity duration and travel behaviors in terms of daily trip numbers and travel time?

• how do the individual allocate the activity-travel time when confronting conflicts from family?

• Interaction and difference between heads’ behaviors.

• What about the influence of socio-demographics?

2007/12/14

4

2.Research reviews•2.1 Conflict of obligation

▫ many literatures examine person allocation to family obligation (Simma and Axhausen, 2001…)

▫ Work-family obligation and Family-work obligation (Osman and Lulu, 2006…)

▫ Travel and family-related stress from conflicts (Gustafson, 2006…)

▫ How to measure obligation conflict: activity time allocation (Gronlund, 2007; Kinnunen and Mauno, 1998…)

▫ Activity categories (Golob and McNally, 1997; Zhang et al. ,2005, 2006; Cilebe and Koppelman, 2005)

2007/12/14

5

•2.2 Intra-household interaction▫the family obligation will allocate to

different members the gender-role based difference in activity-

travel pattern (Jones et al., 1983; Kitamura et al.,1996; Cao and Chai, 2007;)

All household members (Kato and Matsumoto, 2007…)

▫one’s process will be influenced by the other members’ (Golob, 1999; Golob and McNally, 1997; Lu and Pas ,1999; Fujii et al., 1999; Meka et al., 2002; and Bradley and Vovsha, 2005; Zhang et al., 2005,2006; Kato and Matsumoto, 2007; Bhat and Pendyala, 2005)

2007/12/14

6

3.Data

•3.1 Data source

▫come from a two-day time-use diary survey conducted in in middle July, 1997.

▫the sample used in this study reduces to 267 households while we just concern the behaviors in weekdays.

2007/12/14

7

•3.2 Modeling variables

▫The exogenous variables in this analysis can be classified into three categories: background characteristics, family situation and work situation

▫The endogenous variables are four activities duration (Table 2) and travel time and No. of trips of heads

2007/12/14

8

2007/12/14

9

Activity category Activity types recognized in dairy survey in TianjinWork Work

Wok-related

Family maintenance (Fmai.) Daily grocery, market and superstore

Taking care of the older and babysitting

Home-based work such as cooking, cleaning, and yard work

Personal maintenance (Pmai.) Personal business and other non-leisure activities

Meals, bath, hair-cutting etc.

Visiting post office and bank, chauffeuring, medical visit etc.

window shopping, library, book store etc.

Leisure (Leis.) Reading, TV/movie, music, game

Sport, chatting, social visit bring etc.

Scenery watching, social and club activities

Table 2. Activity categories in this study

Note: The numbers in parentheses are abbreviation.Source: Chai et al. (2002)

4. Methodology • Structural equations modeling (SEM) with

observed variables are defined by the system:

• Where▫ y= (m×1 ) column vector of endogenous variables. In this

studies, m=12, ▫ x=( n×1) column vector of exogenous variables. In this studies,

n=9,▫ B= (m×m) matrix of coefficients representing the direct effects

of endogenous variables on other endogenous variables, ▫ = (n×n) matrix of coefficients representing the direct effects

of exogenous variables on endogenous variables, ▫ ζ = (m×1) column vector of errors.

2007/12/14

10

y By x

y

2007/12/14

11

Time for personal maint. activities

Time for family obligation

Time for leisure activities

Time for work obligation

Total travel time Total number of trips

Male

Time for personal maint. activities

Time for family obligation

Time for leisure activities

Time for work obligation

Total travel time Total number of trips

Female

Background characteristics; Family situation; Work situation

Figure. 2 Hypothetical direct effects among socio-demographics, time allocation and travel behavior of

two household heads

Modeling• though some variables cannot fulfill the normal distribution

assumption, the ML method will be still used in this 267 sample case studies. (Golob and McNally, 1997)

• because some exogenous variables in this data contain missing vales and involve continuous and categorical variables, we will first use the expectation-maximization (EM) arithmetic to derive the covariance matrix

• though the flow diagram among the exogenous is not concerned (i.e. fix the covariance matrix of exogenous ), here we freely estimate nine error-term variances of x in the interest of the measure error of the exogenous variables (Hau et al., 2006).

• the LISREL software is used to estimate the model described above.

2007/12/14

12

5. Findings and interpretations• The independent model has a chi-square value of

409.91 with 120 degrees of freedom.

• The value of the estimated model is 20.20 with 96 degrees of freedom. The estimated model significantly improves the independent model (p=1.00).

• Various goodness-of-fit measures, such as RMSEA=0.00 (p=1.00), GFI=0.9929, and CN=1726, also indicate the model fit is good.

2007/12/14

13

2007/12/14

14

MWork. MFmai. MPmai. MLeis. MTrav. MNtri.MWork. Total --

Direct --Indirect --

MFmai. Total -0.2511***Direct -0.2511***Indirect -0.2511***

MPmai. Total -0.1088** -0.1774Direct -0.1533* -0.1774Indirect -0.9347 --

MLeis. Total -0.3462*** -0.2751 -0.0923Direct -0.4294*** -0.2915 -0.0923Indirect 0.0832 0.0164 --

MTrav. Total 0.0794*** -0.1244** 19.2387***Direct 0.0482** -- 19.2387***Indirect 0.0312** -0.1244** --

MNtri. Total 0.0016** -0.0065**Direct -- -0.0065**Indirect 0.0016** --

Table 3. Total, direct and indirect effects between endogenous of household male head

Note: ‘*’: significant at 0.10 level; ‘**’: significant at 0.05 level; ‘***’ significant at 0.01 level

2007/12/14

15

FWork. FFmai. FPmai. FLeis. FTrav. FNtri.FWork. Total -0.8402***

Direct -0.8402***Indirect --

FFmai. Total --Direct --Indirect --

FPmai. Total -0.0300 0.4230***Direct -0.0300 0.3978***Indirect -- 0.0252

FLeis. Total -0.3845** -0.2651*** -0.2162Direct -0.3910*** -0.5022** -0.2162Indirect 0.0065 0.2370 --

FTrav. Total 0.0421 -0.1714*** 17.5624***Direct 0.0421 -- 17.5624***Indirect -- -0.1714*** --

FNtri. Total -- -0.0077***Direct -- -0.0077***Indirect -- --

Table 4. Total, direct and indirect effects between endogenous of household female head

Note: ‘*’: significant at 0.10 level; ‘**’: significant at 0.05 level; ‘***’ significant at 0.01 level

5.1 Intrapersonal conflict and travel behavior • The result shows that there primarily exists the

family-work conflict in females’ daily time allocation while inverse work-family conflict for males. These findings are consistent with Bjornbrg (2002) on Sweeden and Duncan et al. (2003) on Britain and Cao and Chai (2007) (因为工作或者家庭的需求 ( 因 )导致其他活动时间显著减少 ( 果 )，横向比较 t值大小 )

• Maybe Tianjin’s male heads have more work stress while the female have more family stress. (压力是原因 , 冲突是结果 , 所以只作为解释的可能 )

2007/12/14

16

• The total effect indicate that when encountering the work-family conflict, male head seems to be more likely to change the time for leisure, family obligation and personal time with degressive possibility, while the female seems more likely to change the time for work activities than leisure activities. （概率的大小关系，而非主次先后关系，通过纵向比较 t值大小）

• No matter what conflict the heads encounter, the work obligation will increase the travel behavior in terms of total travel time and numbers of trips, while the family obligation reversely reduce the travel time and numbers of trips.

2007/12/14

17

5.2 Interaction between heads

•There exist substitution, companion and complementary effects in activity time allocation and travel behavior between heads▫对应活动都具有直接正效应，非对应则为负。但只有男个人对女个人活动的效应显著。

▫男出行次数越多，女的也越多，同时女的出行时间也越长。

2007/12/14

18

2007/12/14

19

MWork. MFmai. MPmai. MLeis. MTrav. MNtri.FWork. Total 0.1058 -0.0247

Direct 0.0996 --Indirect 0.0062 -0.0247

FFmai. Total -0.0074 0.0294Direct -- 0.0294Indirect -0.0074 --

FPmai. Total -0.0375 -0.0387 0.2882*Direct -- -- 0.2882*Indirect -0.0375 -0.0387 --

FLeis. Total -0.074 -0.0321 -0.0741 0.1283Direct -- -- -- 0.1283Indirect -0.074 -0.0321 -0.0741 --

FTrav. Total 0.0147 -0.0435 -0.0077 5.9519**Direct -- -- -0.0077 --Indirect 0.0147 -0.0435 -- 5.9519**

FNtri. Total 0.0006 -0.0025 0.3474***Direct -- -- 0.3474***Indirect 0.0006 -0.0025 --

Table 5. Total, direct and indirect effects between endogenous of heads

Note: ‘*’: significant at 0.10 level; ‘**’: significant at 0.05 level; ‘***’ significant at 0.01 level

5.3 Influence of socio-demographics on obligation and travel•The effects of socio-demographics on

them are all insignificant except the impact of the presence of children under 6 on female’s personal maintenance.

2007/12/14

20

6. Concluding discussion• Description and interpretation of conflict process

about family are holistically present but it is better to make clear the process of intra-household decision-making mechanism in view of intrapersonal conflict.

• More household members should be considered in the model to capture more information of intra-household interaction.

• How to use activity to measure demand and obligation depending on the activity categories? Considering the in-home and out-of-home partition.

2007/12/14

21

2007/12/14

22