Transporte mediado por vectores moleculares

To raise a sufficiently large sample to obtain robust model estimates and childcare prices, three waves of HILDA have been pooled together to form the

cross-sectional sample data.29 _{HILDA waves 9 to 11 were selected to form the}

data set for analysis, corresponding with the period between 2009 and 2011.30

For each non-working individual, an expected wage rate is imputed from the Heckman wage model discussed in Section 3.2.3. To improve data quality, a selection criteria is implemented to reduce the number of low quality sample observations. This affects individuals earning less than half of the minimum wage rate or those above the 99th _{percentile of wage distribution, since these}

observations are likely influenced by measurement error.31 _{Observed wage}

rates for individuals who meet the selection criterion are replaced by predicted values of the Heckman wage model.

TABLE 4-1SAMPLE FORMULATION AND NUMBER OF OBSERVATIONS

SELECTION CRITERIA NUMBER OF OBSERVATIONS

Married or de facto couples 8,198

Exclude if the youngest child is older than 12 years -4,353 Exclude if the number of children is more than 6 -2 Exclude self-employed and negative non-labour income -1,304

Exclude full-time students -57

Exclude missing key variables -690

Exclude observations with excessive working/parenting hours (>100 p.w.) -15

Number of observations in the sample 1,777

Source: HILDA wave 2009 – 2011.

The process of generating the sample involves steps indicated in Table 4-1. The sample formulation begins with choosing partnered (married or de facto) couples aged between 25 and 59 years. The sample is further restricted to

29 _{The formation of cross-sectional data by pooling three waves of HILDA has also been applied in earlier studies; see}

for example, Breunig et al. (2008) and Breunig et al. (2012).

30 _{One reason that this thesis does not utilise HILDA waves prior to 2009 was that the childcare policy context}

changed significantly in 2009. In particular, the reimbursement rate of out-of-pocket childcare expenses of CCR increased from 30 percent to 50 percent in 2009, with the maximum payable benefit per child lifted from $4,354 to $7,500 per annum. The CCR benefits in the post-2009 period significantly lower childcare costs for many eligible households in terms of both hourly childcare prices and total benefits received.

31 _{The minimum wage is set to $14 per hour for both females and males, reflecting the level of payment rate}

implanted in 2009 (Sloane, 2010). The 99th _{percentile of the wage distribution is $55.56 per hour for females and}

households with at least one child aged 12 years or younger. Two observations with more than 6 children are dropped because of increasing complexity of imputing income support benefits. The self-employed and negative non-labour income earners are excluded because of poor data quality on income and hours. If one of the spouses is a full-time student, the household is excluded because full-time students are likely to face a different set of time constraints. Individuals with missing self-completed questionnaires and other key variables are excluded. Excessive reported hours of work and parental care are likely due to measurement error and are excluded, affecting a total of 15 individuals who report more than 100 hours in either work or parental care. The final sample consists of 1,777 couple households across three waves. The time-spent in parental care and informal care is calculated based on the appropriate time aggregation across childcare usage of each arrangement. The information on time-spent in different childcare activities is collected in the household questionnaire and time-spent in parenting activities is reported in the self-completed questionnaire.32 _{If a household does not use a specific type}

of childcare, this is associated with a time-use value of zero.

4.4.1. Discretising Choice Set

Central to the discrete choice approach is the defining of a finite number of hour-choices. There is no obvious way to map continuous hours into discrete states. The standard practice is to place the observed hours to their nearest discrete points.33 _{Many earlier studies that attempt to quantify the sensitivity}

using different discrete points have found that their main results are insensitive to the rule that is used to assign discrete hour points (Van Soest, 1995; Van

32 _{The response rate to the household questionnaire is slightly higher than the self-completed questionnaire. A total of}

55 households (3 percent) are excluded due to incomplete information on the time-spent in parenting activities, leaving a final sample size of 1,777 observations.

Soest et al., 2002). However, it is obvious that increasing the number of discrete points reduces rounding errors. Van Soest et al. (2002) suggest that using four discrete points provides a reasonable mapping of the distribution of working hours.

FIGURE 4-1HISTOGRAMS OF WEEKLY HOURS WORKED (PARTNERED PARENTS)34

Figure 4-1 presents the histograms of hours worked by both parents. For mothers, the majority of hours occur between zero and 45 hours per week. Most spikes are clustered between 20 and 40 hours. Fathers typically do not work part-time and their actual working hours are heavily concentrated between 35 and 50 hours per week, corresponding to full-time employment. To formulate discrete choices for female labour supply, the lower limit of the choice set is set to zero hours, representing inactivity in the labour market. Discrete hour points are formulated in an equal distance between zero and an upper limit. In the male chauvinist specification, ten discrete choices are formulated at multiples of five hours with the upper limit of 45 hours per week to provide a good coverage of the observed pattern. Females who report hours worked between 45 and 100 hours are rounded to 45 hours. This rounding affects a total of 60 observations (3 percent).

34 _{Non-working individuals are excluded from the histogram.} 0 0.02 0.04 0.06 0.08 0.1 0.12 0 10 20 30 40 50 60 70 80+ D e n s it y

Hours Worked Per Week (Female)

0 0.05 0.1 0.15 0.2 0.25 0 10 20 30 40 50 60 70 80+ D e n s it y

In the dual-agent model, the number of discrete choices expands dramatically because the decisions of fathers are accounted for. Five discrete points are set up for hours worked at multiples of 16 hours from 8 to 56 hours per week for both males and females. A total of 75 fathers (4 percent) who reported working hours between 56 and 100 hours per week are rounded to the largest discrete point.

FIGURE 4-2HISTOGRAMS OF WEEKLY PARENTING HOURS (PARTNERED PARENTS)

Figure 4-2 presents the distribution of weekly parental care hours by both spouses. Note that HILDA is not a time use survey and the survey respondents self-report their weekly time-spent in parenting activities alongside other activities. Spikes are observed in multiples of ten hours, which suggests that survey respondents may experience difficulties in reporting their actual time- spent in parenting activities and tend to round the reported values to multiples of ten.

The discrete points are purposely formulated in multiples of ten hours to match the observed spikes in the sample data. In the male chauvinist specification, ten discrete points are formulated for mother’s parental care hours (5 hours to 95 hours per week). In the dual-agent specification, fewer discrete points are formulated to keep the size of the choice set manageable. The five discrete points formulated for mothers’ parental care hours are in equal periods of 20 hours, ranging from 10 to 90 hours per week. Four discrete

0 0.02 0.04 0.06 0.08 0.1 0.12 0 10 20 30 40 50 60 70 80+ Density

Weekly Hours of Parental Care (Female)

0 0.05 0.1 0.15 0.2 0 10 20 30 40 50 60 70 80+ Density

points are formulated for fathers’ parental care hours, which correspond to 3, 9, 15 and 21 hours per week.

The total number of discrete choices in the male chauvinist specification is 100 and in the dual-agent specification the total number is 600.35 _{Once the}

discrete choice set is formulated, the observed hours are replaced by the nearest discrete value. However, the observed labour supply may not be optimal if individuals are limited in their labour market by demand side factors. Some studies replace the actual hours worked by the desired hours to remove the demand side factors (Bingley & Walker, 2001; Euwals & Van Soest, 1999). This approach is not followed because the reported time-spent in parental care is associated with the actual hours worked.

4.4.2. Descriptive Statistics

Table 4-2 presents the descriptive statistics of the personal information of the parents in the sample data.

35 _{In the male chauvinist specification, there are ten discrete points in both ℎ}

𝑚 and 𝑐𝑚, and the number of different

choices is given as 10 × 10 = 100. In the dual agent specification, ℎ𝑚, ℎ𝑓, 𝑐𝑚, and 𝑐𝑓 are discretised into 5, 5, 6 and

TABLE 4-2DESCRIPTIVE STATISTICS OF PERSONAL INFORMATION

PERSONAL

INFORMATION DESCRIPTION

MOTHER FATHER

Mean Std.Dev. Mean Std.Dev. Age indicators

Age Age in years 36.31 (6.56) 38.57 (7.26)

15-20 1 if aged between 15-20 0.00 (0.05) 0.00 (0.02) 20-25 1 if aged between 20-25 0.03 (0.18) 0.01 (0.11) 25-30 1 if aged between 25-30 0.13 (0.34) 0.09 (0.29) 30-35 1 if aged between 30-35 0.22 (0.41) 0.19 (0.39) 35-40 1 if aged between 35-40 0.30 (0.46) 0.28 (0.45) 40-45 1 if aged between 40-45 0.21 (0.41) 0.22 (0.41) 45-50 1 if aged between 45-50 0.08 (0.28) 0.13 (0.33) 50-55 1 if aged between 50-55 0.02 (0.15) 0.06 (0.24) 55+ 1 if aged 55 or more 0 (0) 0.02 (0.13) Education

University 1 if postgraduate, graduate, bachelor or honours

0.37 (0.48) 0.32 (0.47) Vocational 1 if diploma or certificates I/II/III/IV 0.28 (0.45) 0.45 (0.50) Year 12 1 if year 12 0.19 (0.39) 0.12 (0.32) Year 11 1 if year 11 or less 0.16 (0.36) 0.12 (0.33) Employment

Employed 1 if currently employed 0.62 (0.48) 0.94 (0.25) Full-time 1 if employed full-time 0.21 (0.41) 0.89 (0.31) Part-time 1 if employed part-time 0.41 (0.49) 0.04 (0.20) Hours worked Hours worked per week if employed 26.90 (12.47) 44.87 (9.99) Gross wage Gross wage rate per hour if employed 30.05 (23.11) 35.30 (18.17) Work experience Time spent in paid work in years 13.31 (7.03) 19.03 (7.83) Non-labour income Non-labour income p.a. (000s) 1.45 (6.50) 2.78 (15.83) Parental care

Provision of care 1 if parental care is provided 0.99 (0.07) 0.99 (0.11) Hours provided Hours of care per week if provided 30.57 (23.32) 14.04 (11.39) Dissatisfied

workload

1 if unsatisfied with the way parental care tasks are divided between parents

0.18 (0.18) 0.10 (0.29) Health

Health improved 1 if reported health better than one year ago 0.18 (0.39) 0.16 (0.37) Health worsened 1 if reported health worse than one year ago 0.11 (0.31) 0.10 (0.30) Long-term

disability

1 if any long-term health conditions that limit the type or amount of work

0.08 (0.28) 0.07 (0.26) Other characteristics

English speaking 1 if born overseas and learned English as the first language

0.10 (0.30) 0.12 (0.33) Born in Australia 1 if born in Australia 0.76 (0.43) 0.77 (0.42)

Observations 1,777

Households Number of households 975 Source: HILDA wave 2009 – 2011.

Note: Cross-sectional analytical weights applied. The non-labour income is defined as the sum of business income, investment income, private pensions and private transfers as reported in the financial year preceding the interview.

The descriptive statistics are largely in line with a priori expectations. With respect to education, most mothers (37 percent) reported having a university degree as their highest educational attainment, compared to fathers (32 percent), whereas 28 percent of mothers are recorded as having a diploma or certificate as their highest attainment, compared to 45 percent of fathers.

As the sample is confined to two-parent households, the female employment rate is relatively low. Around 62 percent of mothers and 94 percent of their partners report being employed. Among those who are employed, the average of hours worked is much higher for males than for females. Approximate 89 percent of males are full-time workers, 4 percent are part-time workers and on average males work 45 hours per week. In contrast, 21 percent of mothers are employed full-time, 41 percent are employed part-time and the average number of hours worked per week is 27 hours. The average reported gross wage rate is $35 per hour for fathers - around five dollars higher than the reported wage for mothers. The average non-labour income per annum is around $1,400 for mothers and $2,800 for fathers and is defined as the sum of business income, investment income, private pensions and private transfers as reported in the financial year preceding the interview.

Table 4-3 describes the summary statistics of household demographics and childcare usage.

TABLE 4-3DESCRIPTIVE STATISTICS OF HOUSEHOLD DEMOGRAPHICS

HOUSEHOLD DEMOGRAPHICS DESCRIPTIONS MEAN STD.DEV.

Marital status

Married 1 if legally married 0.81 (0.40) De facto 1 if de facto 0.19 (0.40) Employment

Both parents working 1 if both parents are working 0.61 (0.49) Working father, non-working mother 1 if only father is working 0.32 (0.47) Non-working father, working mother 1 if only mother is working 0.03 (0.18) Both parents non-working 1 if neither parent is working 0.04 (0.20) Number of children by age groups

0-1 years Number of children aged between 0-1 0.31 (0.49) 2-5 years Number of children aged between 2-5 0.59 (0.70) 6-9 years Number of children aged between 6-9 0.49 (0.67) 10-12 years Number of children aged between 10-12 0.37 (0.56) 13-17 years Number of children aged between 13-17 0.27 (0.57) Use of childcare

Parental care 1 if parental care is provided 1 (0) Informal care 1 if informal childcare is used 0.27 (0.45) Formal care 1 if formal childcare is used 0.28 (0.45) Usage of childcare (if used)

Parental care Hours of care per week 44.61 (44.61) Informal care Hours of informal childcare per week 16.21 (16.21) Formal care Hours of formal childcare per week 22.05 (22.05) Other childcare variables

Difficulty assessing childcare 1 if finding a place at childcare centre is difficult

0.21 (0.21) Difficulty coordinating multiple childcare 1 if difficult to juggle multiple childcare

arrangements

0.22 (0.22) State

NSW 1 if resides in NSW 0.29 (0.29)

VIC 1 if resides in VIC 0.23 (0.23)

QLD 1 if resides in QLD 0.24 (0.24)

SA 1 if resides in SA 0.06 (0.06)

WA 1 if resides in WA 0.12 (0.12)

TAS 1 if resides in TAS 0.03 (0.03)

NT 1 if resides in NT 0.01 (0.01)

ACT 1 if resides in ACT 0.03 (0.03)

Observations 1,777

Source: HILDA wave 2009 – 2011.

Note: Cross-sectional analytical weights applied.

The majority of sample households are married couples, with both parents working (61 percent). In terms of childcare, all households report time-spent in parental care, with a weekly average of approximately 45 hours. As expected, the mother is the dominant caregiver in the household. The average parental care undertaken by mothers is 30 hours per week and parental care undertaken by fathers is around 14 hours per week. About a quarter of households rely upon at least some informal or formal childcare. The average time-spent in informal care is 16 hours per week and 22 hours per week in formal care. The data shows considerable variation in the availability of

childcare services. Approximately 21 percent of households report difficulty in finding a place at local childcare centres, and 22 percent of households find coordinating multiple childcare arrangements difficult.