DISCUSSION PAPER SERIES
September 2014

No.2014-10

The long working hour and a positive utilizationof part-timers

Atsuyuki Fukaura

The long working hour and a positive utilization of part-timers
Atsuyuki Fukaura
Abstract:
The long working hour of Japanese workers has been nation widely known and it isstatistically confirmed as well. By referring the official statistics we found that when
the total working hours are increasing, working hours of full-timers are decreasing
and increasing for part-timers. This symmetric behavior suggests part-timers isimportant channel for adjusting the total working hours, because the working terms
for full-timers is not easily revised. By utilizing part-timers and combining them tofull-timers, it becomes possible to pursue the flexible working hour management andit leads, as a consequence, the reduction of total working hours. There is no likelihoodof any immediate improvement to the long working hour in local economy, however,reconsidering the method to utilize part-timers may be the first step for establishing
the appropriate and efficient labor managements.
Keywords:
part-timers

full-timers working hours

1. Introduction
The long working hour of Japanese workers is widely known. In Nagasaki
prefecture, the west end of the Japanese archipelago, Monthly Labor Statistics Survey
released by Ministry of Health, Labor and Welfare(MHLW) shows the total working
hours were 1889hrs(2005), 1896hrs(2006),1889hrs(2007),1919hrs(2008), 1927hrs(2009),
1927hrs(2010), 1876hrs(2011). Especially in the three years since 2009, Nagasaki hasrecorded the longest hours among the nation.
These results have caused a huge argument among workers (unions), the Chamberof Commerce, the local authorities, prefectural and municipal assembly and the local
office of MHLW. Some unions emphasized the possibility that the low wage have forced
to workers to work longer to support their households, regardless of a high laborproductivity. On the other hand, the managements denied it because the over 40hours
per week were not allowed under the legal restriction, instead, emphasized the low
productivity of workers and an overall inertia of the local economy. Further, becausesome members of assembly suspected the accuracy of the statistics, then the local office1

of MHLW has checked it but could not find any significant errors, though there wassome incompleteness in the replacement of the sample. However, prior attempts to show
the causes have been inconclusive.
Fukaura (2012) focused on the relation between the employment pattern and theworking hours, and confirmed the hypothesis that the business was not utilizing thediversification of the employment pattern efficiently enough to shorten the working
hour. Fukaura (2013b) also estimated the labor-productivity of Nagasaki workers
and found it was not as high as workers insisted. Moreover, as to the discussion
saying the minimum wage of Nagasaki is unfairly low, it was found that the current
procedures for setting the minimum wage were not so irrational so the local
economic factors are relatively fairly considered, although not perfectly (Fukaura(2013a)(2013c)). These show the possibility that the causes of the long working hour
are the local factors, then both of business and workers can improve theiremployment environments by themselves.
If the working hours are determined and influenced by local factors, then acorrect measurement of the working hours in each region is a first step for
analyzing the causes and effects of long working hour. The discussion we develop
below is an attempt to examine MHLW’s estimation method and results, and thenwe will go on to discuss the causes of long working hour in Nagasaki which is one of
the typical example of the weak local economy.
2. Re-calculation of working hours
We do not know exactly how MHLW calculates the total working hours for all
prefectures. However, it is possible to infer it by checking the original data used there.
Table 1 presents the inferred procedures.
In the statistics of MHLW, sample firms collected are divided to two categories, thefirms with 30 employees or more and the firms with 5-29 employees. Further, these are
divided into full-timers and part-timers. First, annual working hours and working days
are used to calculate the working hours par day (=annual working hours/ working days).
For example in 2005, as to smaller firms, we have 8.15hrs for full-timers and 5.53hrs forpart-timers. Similarly, for larger firms, 8.29hrs for full-timers and 5.46hrs forpart-timers are derived.
In order to estimate the total working hours, we have to take into account the ratioof full-time worker and part-timers workers. Then we calculate the weighted average ofworking hours by using this ratio as a weight. Take 2005,
2

full-timers, smaller firms forinstance, 2062×0.795+1217×0.205=1639.29+249.49=1888.78. Iterating the similarcalculations yields the numerical values for each year (Table 1).
The total working hours by our estimations and the total working hours reported
by MHLW (bottom row of Table 1) are graphed by Figure 1, from which we can derivesome implications.
First of all, Figure 1 confirms that the officially reported total working hours is the estimation
concerning a relatively small-scale firm (the reasons why the value of 2008 does not identical areunknown). This might be because smaller firms of 29 people or less account for around 95% of all
firms, workers employed by smaller firm are around 60% of all workers.
Second, we have to note the total working hours of larger firms are longer than those ofsmaller firms. In larger firms, we can see from Table 1 that the working hours of full-timers(part-timers) are generally longer (shorter) than the small firms. Because the ratio of full-times ishigher in the larger firms, then there is a possibility that resulted values are influenced by the larger
firms’ working hours.
In third, both series show the drastic decrease of the working hours from 2010 to 2012. By
examining Table 1, total working hours estimated(5-29) are decreased by around 12% between 2010
and 2012 and by around 11% from 2011 to 2012 for the larger firms(see Figure 1). These are very
impressive events and in the autumn in 2013 it was reported broadly that Nagasaki returned thedisgrace of longest working hour.
.
(hrs.) 2000
1950
1900
1850
1800
2005 2006 2007 2008 2009 2010 2011 2012
total working hours (30-)
total working hours (5-29)
total working hours reported

Figure 1 total working hours
However, in order to conclude the working conditions and environments are significantly
improved in Nagasaki, we have to consider the background reasons from the view points of the3technical constraints in the statistical research and the characters of local labor market.
The former is related to the technical constraints which are inevitable when we sample firms
from the entire. In Monthly Labor statistics Survey, the sample firms are shuffled in every
2~3 years and some are replaced to another, in order to remove the influence of thespecific firm. Hence, when the large firm with short working hours is chosen by chance,
it affects the results significantly. According to the Nagasaki office of Labor Bureau, thepossibility that a new sampling conducted in 2012 had an influence is undeniable.
Especially in Nagasaki where the number of large firms is less than that of themetropolitan area, the population of the large firms from which the sample firms are
drawn is small. So this kind of sample bias has a significant influence in the calculationof larger firms’ value.
If this bias would have caused similar effect in all prefectures, then the working
hour in other areas in recent few years would be miscalculation, which causes the doubtthat Nagasaki would not be the worst. At present, there is no way to confirm it, hence
we have to rely on Table1 as the only accessible dataset. This may lead to incorrectconclusions, but we can extract some findings for working hour management.
3. Ratio of part-timers and the total working hours
As noted above, a simple and direct comparison of total working hours cannot
capture the accurate findings. Therefore, we have to search the background factors
which reduced the total working hours, by considering the labor market structures.
Note the behaviors of each row of Table 1 after 2010. There is a considerable differencein the movement between full-time and part-timers. For example, working hours(Y) of
full-timers (5-29) are decreased only 28 hrs. since 2010, but that of part-timers are
decreased around 100 hrs. The working days (5-29) are decreased by 2 days and 11 days,
respectively. However, for working hours(D), we cannot see such a big difference, that is,differences are only 0.04 hrs.(≒3 minutes) and 0.13 hrs.(≒8minutes) respectively. A
similar trend is observed in the larger firms too.
The most striking feature is the behaviors of working hours estimated (see Figure
2 and Figure 3). At a glance, we can understand that two figures are almost symmetricvertically, which means working hours of full-timers has been decreasing during that
periods, and that of part-timers has been increasing. By referring the Figure 1 too, it is
the reduction of working hours of full-timers that have contributed to the reduction of
total working hours. This seems to contradict the fact of the increased working hours ofpart-timers, however, we can explain this contradiction by noting the rapid increase of4the ratio of part-timers.
(hrs.) 1750
1700
1650
1600
1550
1500
1450
2005 2006 2007 2008 2009 2010 2011 2012
full time (30-)
full time (5-29)

Figure 2 total working hours estimated (full-timers)(hrs.) 380
360
340
320
300
280
260
240
220
200
2005 2006 2007 2008 2009 2010 2011 2012
part time(30-)

part time(5-29)

Figure 3 total working hours estimated (part-timers)
According to the data classified by industries, an increase in the ratio of parttimers in medical/welfare industry and in hotel/restaurant businesses is remarkablesince 2010. Because part-timers are working normally shorter than full-timers, then it
is straightforwardly understood that total working hours are decreased when the ratioof part-timer is increased.
Working hours per day are relatively constant as noted above. Because theworking conditions of full-timers cannot be changed easily, then the numbers ofpart-timers are the almost only channel to adjust the total man-hours or personal
expenses. This may result in the reduction of total working hours.

5

4 Graphical explanations
We found that when the total working hours are increasing, working hours offull-timers are decreasing and increasing for part-timers. This symmetric behavior
suggests part-timers is important channel for adjusting the total working hours,
because the working terms for full-timers is not easily revised. By utilizing part-timers
and combining them to full-timers, it becomes possible to pursue the flexible working
hour management and it leads, as a consequence, the reduction of total working hours.
Figure 4 presents the theoretical foundations of above discussion.
Yield
Ymax

Y=F(L)
Yp

Yf

Yp*

Yf*

Lp*
Lp

Lf*

Lf L*

Lmax

working hours

Figure 4 full timers and part timers
In Figure 4, Y=F(L) is the well behaved production function, which shows Ymax is
produced if Lmax is employed. Consider the situation that the firm substitutes fulltimers whose marginal productivity (MP) is relatively low to part-timers with similar
low MP. In this case, firm attains Yf(<Ymax) by employing Lf of full-timers and Lp ofpart-timers produce (Ymax-Yf). The wage of part-timers is lower because of their low
MP. However, because total working hours and total wage bills are not changed, there isno incentive for firms to take such an employment strategy. Therefore, a simple
substitution of the unskilled labor (jobs with low productivity) of by full-timers to6

part-timers is unattractive for the firms.
However, when the high skilled part-timers are available, Ymax can be realizedwith lowering the total working hours. Here the “high skilled” means that part-timers
have the same production function as full-timers. Then Lf* of full-timers and Lp* of
part-timers are employed and produces Yf* and Yp* respectively ( Yf*+Yp*=Ymax).
Total working hours are L*(<Lmax). Needless to say, the firms can employ more small
number of high skilled part-timers, with keeping full-timers to Lf (shown by small
dotted line).
.
5 Regression analyses
Above discussions suggest that the behavior of part-timers is important channel
for adjusting the total working hours. Here, "the behavior of part-timers" should be
examined from three dimensions, i.e., the working days, the working hours per day andpart-timers’ ratio. In what follows, we conduct the regression analysis in order toconfirm if the behaviors of part-timers have a significant correlation with the total
working hours.
The structures and the results of the regressions are shown in Table 2. Independent
variables and dependent variables are(independent variables)
estWH(Y)part: estimated working hours (year), part-timers
estWH(Y)full: estimated working hours (year), full-timers
est-total WH(Y): estimated total working hours estimated= estimated working hours (year), part-timers+ estimated working hours (year), full-timers
repo-total WH(Y): total working hours reported by MWHL
(dependent variables)
WDpart: working days (year), part-timers
WH(D)part: working hours oar day, part-timers
Partratio: ratio of part-timers
WDfull: working days (year), full-timers
WH(D)full: working hours oar day, full-timers.

7

WDpar

WH(D)part

Partratio

WDfullWH(D)full(5-29)(5-29)(5-29)(5-29)(5-29)

estWH(Y)part

1.0006***1.0290***0.9792***(5-29)(18.41)(42.37)(76.66)variables

①

②

③

④

⑤

⑥

ad.R2

independent variables

dependent

0.99

estWH(Y)full-0.3092***

1.2390***1.4374***(5-29)(-26.98)(8.44)(5.76)

est-total

0.13770.2409*-0.0890(0.58)(2.23)(-1.612)

WH(Y) (5-29)

repo-total

0.8926**

1.9195***(-7.34)(3.94)(4.98)

0.1592-0.0814(0.99)(1.38)(-1.38)WH(Y)(5-29)

0.72-0.1298***
0.2448

0.99

0.95
0.69

-0.1417***0.8991*

1.2136(-5.25)(2.60)(2.06)

0.88

Table 2-1 regression results (5-29)

WDpar

WH(D)part

Partratio

WDfullWH(D)full

(30-)

(30-)

(30-)

(30-)

(30-)

estWH(Y)part(31.1093***

1.0279***0.9062***0-)(6.42)(19.98)(26.46)variables⑦⑧-0.2331***1.1109***1.0877***(30-)(-118.39)(27.30)(25.80)

est-total

0.17520.1427-0.1045*(0.77)(2.09)(-2.31)

WH(Y) (30-)
⑩

⑫

0.99

estWH(Y)full

⑨

⑪

ad.R2

independent variables

dependent

repo-total

1.026

0.9766(-3.59)(1.45)(1.33)

0.0206-0.0492(0.12)(0.11)(-0.44)

WH(Y)
(30-)

0.95

-0.1228**0.0686

0.99

0.92

0.40

-0.0872*-0.6062

0.7668(-2.20)(-0.74)(0.90)

0.69

Table 2-2 regression results (30-)(significance level of 1%:***,5%: **,10%:*)Among these results, regression ①, ②, ⑦ and ⑧ are trivial. Because its
dependent variables are calculated by the independent variables as explained in Table 1,8

it is natural that all dependent variables are statistically significant. However, anegative coefficients of Partratio in ② and ⑧ are worth to note because this means
the working hours of full-timers are decreased as the share of part-timers to the total
workforce grows. This suggests that part-timers are the substitution to full-timers.
From these results, we can extract some implications for reducing the total
working hours.
1. For smaller firms, it is effective to reduce the daily working hours of part-timers
because of the negative coefficient of ③. The sign of WH(D)part(30-) is positive but
the t-value is relatively large, so the same implication can be derived for the larger
firms.
2. WDfull(5-29) and WH(D)full(5-29) are statistically significant and positively

correlated with the independent variables of ④. Therefore, an increase of theoff-day (holidays, vacations) is effective, in addition to reducing the overtime duties.
This supports the conclusions of Fukaura(2012a), where the author discussed thefive-day work week system has not introduced broadly in Nagasaki yet, especially at
the small-size firms, and this contributes to make the total working hours longer
than national average.
3. The coefficients of Partratio are statistically significant and negative in ④ and ⑩.

The implication is the same as ② and ⑧.
4. Although WDfull(30-) and WH(D)full(30-) are not statistically significant in ⑩, thesigns are positive. Together with the above discussions, this means the five-day
work week system and overtime duties are the key factors for the improvement oflong working hour.
In summary, the important findings are as follows. First, because part-timers'
working hour is normally shorter than full-timers, then it is intuitively expected that asubstitution between part-timers and full-timers decreases total hour worked. Second,
for full-timers, the reductions of working hours and the working days are effective.
Needless to say, it is impossible to do this only by a revision of full-timers' working
conditions unless the load of full-timers is substituted for part-timers. Here, it is worth
to notice that part-timers “substitute” full-timers, not “complement” full-timers.
In other words, part-timers are different from full-timers not because they engage
in the different jobs, but because their working hours are different. Therefore, it isideally preferable that the skill of both is equal. For this case, the firms can introduce
multiple work systems based on worker's attribute, and can selectively employ theworkers who prefer part time job to full time job and the workers who prefer full time9

job to part time job. By utilizing part-timers and combining them to full-timers, it
becomes possible to pursue the flexible working hour management and it leads, as aconsequence, the reduction of total working hours.
Here we have to remember, because these regressions do not include any variables
representing the productivity, we cannot confirm the theoretical predictions depicted in
Figure 4. However, from above results that an increase of part-timers’ ratio brings the
reduction of total working hours, we can infer that part-timers are playing theimportant role as the complement working force, in the sense that their productivities
are almost same as full-timers, especially at the small firm.
5 Concluding remarks
Throughout the course of this essay, we can extract the conclusions that promoting
the five day work system and an effective combination of full-timers and part-timers (asa result part-timers’ ratio is increased) are expected to reduce the total working hours
and improve the overall working environments.
Needless to say, the reduction of working hours/day deteriorates the performanceof the firms if the improvement of labor productivity does not occur. Though the laborproductivity of Nagasaki is nearly the bottom in Japan, this means the room for
improvement is large.
Nowadays, part-timers and dispatched workers are classified into temporary
workers. If we focus only the difference of daily working hours, part-timers aretemporary. However, if we focus on the similarities of the jobs both workers engage in, it
will be necessary to think part-timers as the key factor of the various employment
system. It is effective in the reduction in total working hours to establish the effective
substitution between part-timers and full-timers.
This requires a high elasticity of substitution between part-timers and full-timers.
This is not difficult in industries where the high skilled professions are needed. For
example, in Japan, doctors or nurses are engaging in the long hour job. However, somefemale doctors and nurses often retire in the early stage of their careers because of
marriages and child caring. But after their children grow up, as the part-timers, they
can spare their time to substitute the incumbent doctors. Or they can engage in the
supplemental medical jobs, for example, the medical consulting or Health Supervisor forthe locals, because they are officially qualified as a profession. It is beneficial for themand the incumbents, because they can utilize their free time and the incumbents can
reduce their job load.
10

Of course, this may be a special and lucky example and cannot be directly appliedin other industries. However, in order to reduce the total working hours without loss of
productivity, it is effective to regard part-timers as the pivotal work force, not as thefringe workers, and improve their skills enough to substitute perfectly to full-timers.
There is no likelihood of any immediate improvement to the long working hour inlocal economy, however, reconsidering the method to utilize part-timers may be the firststep for establishing the appropriate and efficient labor managements.
References
Fukaura, A.,2012, “A five day work week system and labor productivity/efficiency”¸Discussion Paper Series 2012-6, Faculty of Economics Nagasaki University
Fukaura, A., 2013a, “Rationality of the Guideline System in the Japanese Minimum
Wage Law”¸ KEIEI TO KEIZAI¸ Vol.92, no.44, pp1-28
Fukaura, A., 2013b, “Are Workers in Nagasaki Over-Working without Enough Reward?”,KEIEI TO KEIZAI¸ Vol.93,no.1/2, pp.267〜286
Fukaura, A., 2013c, “The guideline system of the Japanese minimum wage law and theregional economy – Does it have a statistical validity? –”, The Joint Journal of the

National Universities in Kyushu, Education and Humanities, Vol.1, No.1, 2013,
pp.1-20.

11

2005

2006

2007

2008

2009

2010

2011

2012

full-time workers(5-29)

2062

2105

2090

2077

2095

2106

2098

2078

part-time workers(5-29)

1217

1217

1232

1246

1346

1316

1252

1224

working

total working hours(5-29)

1889

1896

1889

1919

1927

1927

1876

1825

hours(Y)full-time workers(30-)

2088

2111

2113

2101

2108

2100

2102

2066

part-time workers(30-)

1250

1258

1393

1474

1392

1403

1400

1204

total working hours(30-))

3338

3369

3506

3575

3500

3503

3502

3270

full-time workers(5-29)

253

257

254

253

253

254

253

252

part-time workers(5-29)

220

218

225

234

229

226

218

215

full-time workers(30-)

252

253

252

250

248

248

250

246

part-time workers(30-)

229

228

228

232

226

228

228

209

full-time workers(5-29)

8.15

8.19

8.23

8.21

8.28

8.29

8.29

8.25

working

part-time workers(5-29)

5.53

5.58

5.48

5.32

5.88

5.82

5.74

5.69

hours(D)full-time workers(30-)

8.29

8.34

8.38

8.40

8.50

8.47

8.41

8.40

part-time workers(30-)

5.46

5.52

6.11

6.35

6.16

6.15

6.14

5.76

full-time workers(5-29)

79.5

76.4

76.4

78.3

77.1

77.3

73.9

70.3

part-time workers(5-29)

20.5

23.6

23.6

21.7

22.9

22.7

26.1

29.7

full-time workers(30-)

81.7

80.1

79.9

80

80.3

81.1

80.5

72.7

part-time workers(30-)

18.3

19.9

20.1

20

19.7

18.9

19.5

27.3

full-time workers(5-29)

1639.29

1608.221596.76

1626.29

1615.25

1627.941550.421460.83

part-time workers(5-29)

249.49287.21290.75270.38308.23298.73326.77363.53working hours

total working hours estimated(5-29)

1888.78

1895.43

1887.51

1896.67

1923.48

1926.67

1877.19

1824.36

estimated

full-time workers(30-)

1705.90

1690.91

1688.29

1680.80

1692.72

1703.101692.111501.98

part-time workers(30-)

228.75250.34279.99294.80274.22265.17273.00328.69

total working hours estimated(30-)

1705.90

1690.91

1688.29

1680.80

1692.72

1703.101692.111501.98

1889

1896

1889

1919

1927

1927

1876

1825

working days

full/part ratio

total working hours reported

Table 1 total working hours (estimated and reported)