2017-5
Why is the Motivation of Non-Regular Employees Not Low?
From the Viewpoints of Equity Theory and Social Comparison
Processes Theory

Mitsutoshi Hirano

Chika Kasatani

Why is the Motivation of Non-Regular Employees Not Low?
From the Viewpoints of Equity Theory and Social Comparison
Processes Theory
Mitsutoshi Hirano
Kobe University, Graduate School of Business Administration
Chika Kasatani
Kobe University

Abstract

The aim of this study is to use perspectives from equity theory and social comparison to
explain the reason why non-regular employees’ motivation is not low, despite working at
relatively low pay compared to regular employees. To achieve this, the study conducted aquestionnaire survey of regular (full-time) and part-time employees of a grocery store chain
retail business. The results indicated the following: (1) part-time workers have greater
motivation, affective commitment, and job satisfaction than regular workers; (2) increased
perception of distributive justice leads to greater motivation, affective commitment, and job
satisfaction; (3) part-time managers can be divided according to their choice of comparativereferent between a group that chooses fellow part-time managers, a group that chooses regular
employees (upward comparison), and a group that chooses part-time workers (downward
comparison); and (4) there is a greater tendency for male part-time managers to make upward
comparison than females. Additionally, among female part-time managers, there is a tendency
for single mothers to make upward comparison, and for the “with spouse, without children”
group to make downward comparison. Drawing on these results, the study considered therelation between non-regular employees’ motivation and their choice of comparative referent.
The study also discusses the significance of maintaining systems for transferring from nonregular to regular employee status in order to improve motivation in non-regular employees
who make upward comparisons.

Keywords:
comparison

part-time workers; distributive justice; motivation; equity theory; social

1. Introduction
The number of non-regular employees in Japan has increased from 8.81 million in 1990 to
19.62 million in 2014, and the proportion of the working population in non-regular
employment has now reached 35% (Statistics Bureau, Ministry of Internal Affairs andCommunications 2015). Recently, the wage gap between regular and non-regular employment
has become a terrible problem. Yet there has not been much progress in solving this issue. In
fact, the gap is greater in Japan than in Western countries. Wage levels for part-time workers
in Japan are only around 60% of those for full-time workers. However, this ratio is 90% in
France; 80% in Sweden, Denmark, Germany, and the Netherlands; and 70% in Britain and
Italy (Japan Institute for Labour Policy and Training 2015). Faced with Japan’s wage gap
from these Western countries, the Abe Cabinet decided the “Plan for Dynamic Engagement of
All Citizens of Japan,” which declared that it would, “without hesitation, further prepare forlegal reform toward the realization of equal pay for equal work while paying due consideration
to Japanese employment practices.”
However, there are many studies which have indicated that non-regular employees do notnecessarily have low motivation or low job satisfaction (Chae 2010; Okunishi 2008; Japan
Institute for Labour Policy and Training 2006). The aim of this study is to investigate why
non-regular employees, who work for lower wage levels relative to regular employees, do nothave low motivation in the domestic labor market. The concepts we will focus on here areorganizational justice and social comparison. Moreover, the study sets up the following basic
supposition: the size of wages does not directly determine the non-regular employees’
1motivation; rather, recognition of justice (fairness) in wage distribution may have an effect,
and it may be that non-regular employees compare not with regular employees but with fellow
non-regular employees.
2. Literature Review
2.1 Non-Regular Employees’ Motivation
Through an online questionnaire survey, Hirano (2014) found that there was almost no
difference between regular and non-regular employees in motivation and affective
commitment to their organization, and in fact, non-regular employees had greater job
satisfaction and feelings of justice regarding their treatment.
There are also many studies in the West whereby non-regular employees show
organizational behavior comparable to that of regular employees. For instance, Thorsteinson(2003) undertakes meta-analysis of the organizational behavior of full- and part-time workers,
finding that there is almost no difference between the two in work attitudes, such as job
satisfaction, organizational commitment, and intention to quit. De Cuyper et al. (2008) alsoreach the same conclusion from reviewing existing studies on temporary employment.
This raises the question of why non-regular employees display work attitudes comparable
to those of regular employees. Western studies offer various explanations. For instance, there
are discussions of how there is a lack of understanding of the heterogeneity among non-regular
employees (e.g., form of employment, job description, work hours, whether the choice to workon a non-regular basis is voluntary), and how the stress and hidden costs facing regular
employees tied to “golden handcuffs” have been overlooked (Chae 2010). In other words, highheterogeneity means greater dispersion within groups, possibly obscuring the effect onorganizational behavior. Additionally, some people may be working as regular employees
involuntarily, with the costs of quitting being too high due to “golden handcuffs.”
2.2 Organizational Justice
Faced with this puzzle that “non-regular employees do not decisively have lower motivation
and/or sense of justice than regular employees,” this study focuses on the concept of“organizational justice.” According to Greenberg (1987, 1990), organizational justice comprises“distributive justice” and “procedural justice.” Distributive justice refers to whether the
results of distributing scarce resources among members of an organization are fair. In otherwords, it is an issue of perceived justice in reward distribution: how rewards, such as wages,
bonuses, and promotions, are distributed among employees, and whether employees feel thisto be fair. However, procedural justice refers to the perceived fairness of approaches todecision-making processes. Leventhal (1980) supposes that the perception of procedural
justice results in greater feelings of distributive justice.
The previous study on distributive justice is Adams (1965)’s “equity theory.” He attempted
to offer an explanation of the behavior of people participating in social exchange, based on theconcept of relative deprivation. Relative deprivation is defined as dissatisfaction that arises
according to relative standards based on comparison with others, rather than dissatisfaction
based on absolute standards (Ishida 2015). The origin of relative deprivation theory was social
psychology research concerning the US military personnel. Stouffer et al. (1949) found certain
types of trends in the desire to be drafted at the time of joining the military, according to thevarious profiles of American soldiers. Specifically, they found greater desire to be drafted at
the time of joining the military in soldiers who were younger and unmarried rather than thosealready married and who had graduated from high schools. They then used the concept ofrelative deprivation to provide the following consistent explanation for these trends, which, at
a glance, appear to be varied. “Becoming a soldier is experienced as a great deprivation by
many people. Yet according to differences in comparative standards, the feeling of sacrificing
something is stronger in certain people compared with others.” This is explained more
concretely by focusing on differences in marital status: “Comparing himself with his
unmarried associates in the army, he could feel that induction demanded greater sacrificefrom him than from them; and comparing himself with his married civilian friends, he could
feel that he had been called on for sacrifices which they were escaping altogether. Hence, the2

married man, on average, was more likely than others to come into the army with reluctanceand, possibly, a sense of injustice.”
Relative deprivation was introduced as a concept referring to the “deprivation arising as aresult of comparison within a given frame of participation”; it later came to be clearly tied with“reference groups” 1 as points of comparison by Merton (1957), and became a usefulexplanatory concept in social psychology.
On the other hand, equity theory, based on the concept of relative deprivation, supposesthat an individual will feel their circumstances to be just (fair), having made comparison withthose of others, if they judge the inputs they make to an organization to match the outcomes
they receive. Conversely, the individual will be dissatisfied if they think their reward is notproportionate to their efforts or results (under-compensation) in comparison with others.
Further, if they feel they are being over-compensated compared with others, they will carry asense of guilt. Inputs here can refer to the investment of everything of value that theindividual brings to the organization, including work-related efforts, knowledge, experience,but it may also refer to objective criteria, such as age, form of employment, and social position.
Meanwhile, outcomes refer to what the individual receives, and this corresponds to everythingof value received from the enterprise, such as wages, promotions, opportunities to develop
skills, job security, rank, prestige.
What is important here is that these inputs and outcomes are not the sum of objective
elements, but rather the perception of subjective elements by the actors in relationships ofsocial exchange. Expressions (1) and (2) are expressions of inequity that show conditions of
input-outcome imbalance. Expression (3) shows a relationship of equity.
Expression 1 →Under‐compensation; Dissatisfaction
Expression 2 →Over‐compensation; Sense of guilt
Expression 3 →State of equity; Satisfaction
Note: O = Outcome; I = Input; p = Own; a = Other

Ip and Op are the sum of the personal inputs and outcomes perceived by each individual,
and Ia and Oa are the sum of the inputs and outcomes of another actor who functions as acomparative referent, as perceived by the individual. Expression (1) is the condition of undercompensation, in which the individual feels dissatisfaction. Expression (2) is the condition ofover-compensation, in which the individual feels a sense of guilt. Both are expressions ofinequity. An individual who perceives inequity as in (1) will be motivated to remove theaccompanying cognitive dissonance. One method of doing this is to change their own behavior
or that of the other actor. For example, individuals who perceive injustice (unfairness) may
reduce their own inputs in an attempt to near a state of equity. It is likely that this case will
involve a drop in organizational efficiency. Another method is to change the perception of self
and/or others—one key approach here is to change the comparative referent.
In other words, the sense of distributive justice felt by workers is related to who they
compare themselves with (the comparative referent) within the organization (Folger andCropanzano, 1998).
2.3 Upward and downward comparisonsFestinger (1954)’s discussion of the theory of social comparison processes was the first study
to substantially consider the act of comparing oneself to others. According to the theory ofsocial comparison processes, people have the desire to accurately evaluate their own opinions
and abilities, and when there are no concrete standards, they will evaluate themselves bycomparing with others. In this case, people will tend to compare with others who have similar
1 Thatis, a social group that provides the basis for judgment when individuals determine their beliefs,
attitudes, and values, or seeks guidance for behavior.

3

opinions and abilities to themselves (Festinger, 1954; Ambrose, Harland and Kulik, 1991).
This is because, if their own position matches that of others in similar positions, it is easier tosense the accuracy and appropriateness of their own opinions. Thus, it is natural to think that
regular employees will have greater interest in comparing with other regular employees andnon-regular employees with other non-regular employees.
However, when comparing abilities, people do not necessarily compare with others similar
to themselves, while also making upward and downward comparisons. People make upward
comparison under the influence of a unidirectional push upward, that is, the pressure to
improve one’s own abilities and surpass others. In such cases, there is a tendency for people
to choose others better than themselves as a comparative referent to pursue and overtakethem and to attempt to be in a superior position to these referents. This leads to comparison
with those superior to oneself, that is, upward comparison. Because of upward comparison, if
one’s abilities improve, this leads to positive evaluation of oneself, and increased self-esteem
or pride. However, if one was unable to surpass one’s referent in the contest, one has no choice
but to assess one’s own abilities as lower than those of one’s referent, leading to negative
feelings and a decline in self-esteem.
Meanwhile, the motivation to increase self-esteem and prevent its decline may also lead to
downward comparison. Downward comparison is to compare oneself with others who areinferior or less fortunate. By comparing themselves with others less fortunate, people are able
to increase subjective feelings of happiness. Downward comparison can often be observed inpeople who are experiencing some threat to themselves. Upward comparison tends to motivate
us to raise higher results and improve abilities, while downward comparison tends to instill
feelings of comfort.
3.

Research Questions and Analysis Framework
It is understood that the puzzle of “why non-regular employees do not have particularly low
motivation” is related to perception of justice, and that the perception of justice is influenced
by who is used as a comparative referent. It is not clear, however, whom non-regular
employees use as comparative referents. This study posits the following four researchquestions (RQs).
RQ1: What are the levels of motivation, affective commitment, and job satisfaction among
non-regular employees in comparison with regular employees?
RQ2: Does one’s sense of distributive justice increase motivation, affective commitment,
and/or job satisfaction?
RQ3: Does one’s sense of distributive justice change according to the choice of comparativereferent(s)?
RQ4: What kind of non-regular employees tend to make upward and/or downward
comparisons?
RQ3 and RQ4 are the main issues of this paper; RQ1 and RQ2 have been established for the
purposes of checking whether the findings detailed in previous studies are also supported inthis study, as a step prior to consideration of the main issues.
4. Analysis Method
4.1 Study subjects
To solve the research questions, we conducted survey research of employees of Company A,a retail enterprise whose main form of business operation is supermarkets. Company A has
about 1,700 regular employees and 15,000 part-time employees, and has expanded to around
170 stores mainly in the Chūgoku, Shikoku, and Kinki regions (in southwestern Japan). The
personnel department of Company A worked with us in conducting the survey in June-August
2016 alongside leadership training for store managers, with the aim of learning about theawareness of employees working in stores.
Originally, part-time roles in Company A were strictly those supporting regular employees.
4However, some part-time workers have motivation and abilities comparable to those of regular
employees. Company A has therefore adopted a “part-time manager system” in order tobroaden the scope of part-time worker activity. Part-time managers are defined as people whoare able to handle all roles and duties as responsible figures for single sectors, from the
management of their sector’s sales and profits, to planning their juniors’ duties andmanagement of personnel. Accordingly, there is a mix of regular and part-time managers instores. Wage levels are lower for part-time managers than regular managers, that is, there isa wage gap between regular managers and part-time managers. The sample size is 398 parttime managers and 990 regular managers.
4.2 Variables
Except for demographic factors, such as age and gender, questions were asked for responses
about participants’ circumstances on a 5-point scale (1. Not at all applicable; 2. Not applicable;
3. Unsure; 4. Applicable; 5. Greatly applicable). There were 631 female and 772 maleparticipants. The average age was 42 years. There were 731 participants with spouses and639 without.
The variables used in analysis are distributive justice, motivation, affective commitment,
job satisfaction, and choice of comparative referent. Because sense of distributive justice,
motivation and affective commitment comprise multiple questions, the study createdcomposite variables using simple arithmetic means.
Distributive justice is composed of the following four items: “My reward reflects my effort
put into work,” “My current reward is of an appropriate standard to the work I have done,”“My reward reflects the degree of [my] contribution to the organization,” and “My reward
matches the actual results of [my] work.”
Motivation is composed of the following three items: “I feel a great sense of purpose in mycurrent work,” “I genuinely feel joy in working,” and “I am proud to be doing this work.”
Affective commitment is composed of the following three items: “I am proud to be a memberof this company,” “I feel an attachment to this company,” and “I have a sense of allegiance tothis company.”
Job satisfaction is composed of the following one item: “I am satisfied with my current work.”
The choice of comparative referent is in the question “I keep the following in mind forcomparison when judging whether my own wages are high or low,” with the responses being
1. The treatment of regular employees with the same jobs or positions in the company; 2. The
treatment of part-time managers with the same jobs or positions in the company; 3. The
treatment of part-time workers with the same jobs or positions in the company; 4. The amountof wages required to maintain my own household budget; 5. I do not make particularcomparison with anyone; 6. Other.
The following are used as control variables: “Assigned sector (vegetables and fruits_ dummy;
fish_dummy; meet_dummy; deli_dummy; in-store bakery_dummy; grocery_dummy; dairyfoods_dummy; non-foods_dummy; service_dummy; cashier_dummy; general affairs_dummy),”“age,” “gender,” “years of continuous work since joining the company,” “qualifications,”“regular employee_dummy,” “number of relocation transfers,” “number of changes,” “monthly
overtime hours,” “with/without spouse (with spouse_dummy),” “with/without children (withchildren_dummy),” and “with/without preschool infants (with preschool infants_dummy).”5. Results and Consideration
5.1 Research Question 1 (RQ1)
Figure (1) compares the average values of motivation, affective commitment, and job
satisfaction between non-regular and regular workers.

5

3.4

3.3

3.2

3.1

3

Regular employee

Part-time manager

Motivation

3.13

3.33

Affective commitment

3.27

3.34

Job satisfaction

3.06

3.24

AverageStandard
deviation
Average
Affective commitment Standard
deviation
AverageJob satisfaction
Standard
deviation
Motivation

Regularemployee
3.1339.89556Part-time
Significancemanager
3.3257**.77226

3.2671.879433.3409.75544

3.06
.948

3.24
.902

**

Figure 1: Motivation, affective commitment, and job satisfaction of regular employees andpart-time managers
The average values for regular employees were 3.13 for motivation, 3.27 for affective
commitment, and 3.06 for job satisfaction; the average values for part-time managers were3.33 for motivation, 3.34 for affective commitment, and 3.24 for job satisfaction. Part-time
managers had higher values for each of the factors. The average differences were significant
at the 1% level for motivation and affective commitment. Thus, as stated in previous research,the motivation of non-regular employees in Company A as well is not decisively lower thanthat of regular employees.
5.2 Research Question 2 (RQ2)
To investigate the influence of sense of distributive justice on motivation, affective
commitment, and job satisfaction, a multiple regression analysis was performed with sense of
distributive justice as an independent variable and motivation, affective commitment, and job
satisfaction as dependent variables. As seen in Table 1, sense of distributive justice has asignificant positive effect at the 0.1% level on the three dependent variables. As described inprevious research, sense of distributive justice is an important determinant of theorganizational behavior of employees. In particular, if an employee is able to feel that theirown reward matches their efforts and results when compared with others, their motivation,6

affective commitment, and job satisfaction will increase.

Dependent variables MotivationβIndependent variable

Affective
commitmentβ

Job satisfactionβ

Vegetable and fruits_dummy 0.021

0.023-0.026

Fish_dummy-0.029-0.012-0.044

Meet_dummy-0.028-0.0170.002

Deli_dummy-0.0050.052-0.023In-store bakery_dummy

0.038

0.045

0.003

Grocery_dummy

0.055

0.063

Dairy-foods_dummy

0.079

*

0.053

Non-foods_dummy

0.088

*

0.086

Service _dummy-0.0250.02

Cashier_dummy

0.044

0.081

*

-0.019General affairs_dummy

0.054

0.08

*

-0.013

Age

0.15

**

0.178

**

0.1

Gender

-0.071

†

0.078

†

-0.047

Numberofyears
of -0.065
continuous work since joining
the company-0.119*0.017

Qualifications-0.0520.028-0.061

Regular employee_dummy

0.024

0.015

0.005

Number of job relocations

0.062

0.056

0.069

*

Number of job changes-0.056-0.017-0.081††

Average monthly overtime 0.063
hours

*

0.051

With spouse_dummy

0.118

**

0.053

With children_dummy

0.082

†

0.081

With
infants_dummypreschool -0.037-0.018

†

0.055
0.023

*

0.054
-0.041

†

†

0.013
0.052

†

0.023
-0.019Distributive justice0.311*** 0.35*** 0.321

Adj. R2

0.153

0.158

0.118

F

9.892

*** 10.281*** 7.611******

Numbers are standardized beta (β) coefficients ***p<.001, **p<.01, *p<.05, †p<.1
Table 1: Influence of sense of distributive justice on motivation, affective commitment, andjob satisfaction
5.3 Research Question (RQ3)
The analysis in RQ1 and RQ2 focused on both regular employees and part-time managers.
However, RQ3 and RQ4 analyze comparative referent choice. Thus, the analysis below focuses7

solely on part-time managers.
Regular employees were chosen as a comparative referent by 19.3% of part-time managers,
fellow part-time managers by 34.5%, and part-time workers by 10.7%. Part-time workers arestaff who help managers, handle product displays, order placement, and so forth. Company A
employs around 15,000 part-time workers, but the majority of them are part-time workers.
Figure 2 shows the proportion of part-time managers who chose each comparative referent
option. The ratio of part-time managers who made comparison with regular employees (i.e.,
made upward comparison) is 19.3%. Meanwhile, the ratio of part-time managers who madecomparison with part-time employees (i.e., made downward comparison) is 10.7%.
Other, 3%Regularemployees, 19%
No comparison
with anyone,25%
Amount ofwages needed
for household
finances, 8%Part-time
managers, 34%

Part-time
workers, 11%

Figure 2: Comparative referents for part-time managers
Next, Figure 3 shows the average values for sense of distributive justice when part-time
managers are divided by comparative referent. The regular employee comparison group is
2.57, the part-time manager comparison group is 2.90, and the part-time worker comparisongroup is 3.24. The part-time manager comparison group has a greater sense of distributive
justice than the regular employee (upward) comparison group. Further, the part-time worker(downward) comparison group has a greater sense of distributive justice than the fellow parttime manager comparison group. In other words, sense of distributive justice increases as thecomparative referent shifts from upward to downward. The distributive justice questions ask
whether reward matches efforts and results as regular employees have greater reward thanpart-time managers, while part-time workers have lower reward than part-time managers, itwould be natural to think that those making upward comparison would have lower sense of
distributive justice, and that those making downward comparison would have greater senseof distributive justice.
However, what is important here is that, as indicated by Chae (2010), non-regular
employees are a highly heterogeneous group, and this study has found the difference incomparative referent to be one element of this heterogeneity. The degree of sense of
distributive justice is not uniform for part-time managers; there are differences according to
who is chosen as a comparative referent.

8

3.5
3
2.5
2
1.5
1

Amountof wages
No
RegularneededPart-time Part-time
comparisforemployee
manager workers
on withshouseholanyonedfinances

Sense of distributive justice

2.57

2.9

3.24

3.18

3.38

Other

2.43

Figure 3: Distributive justice by comparative referent for part-time managers
5.4 Research Question 4 (RQ4)
RQ4 concerns “what kind of non-regular employees tend to make upward and/or
downward comparisons.” To this end, the study conducted an exploratory examination of
personal attributes in the analysis framework. The focus was first placed on gender as afundamental personal attribute. Figure 4 divides part-time managers into male and female,and shows the proportions of comparative referent choices for each. Focusing on regular
employees, part-time managers, and part-time workers as comparative referents, the highest
proportion of male part-time managers chose regular employees (26.7%), followed by part-time
managers (16.7%), and then part-time workers (3.3%). Meanwhile, the highest proportion of
female part-time managers chose part-time managers (36%), followed by regular employees(18.7%), and then part-time workers (11.3%). It was shown that while female part-time
managers make comparison with employees in the same position as themselves, more malepart-time managers make upward comparison.

(％) 40

35
30
25
20
15
10
5
0

Amountof wages
PartNoRegularPartneededtimecomparis
employeetimeformanageron withsworkers householsanyonedfinances

Other

Male part-time managers

26.7

16.7

3.3

20

30

3.3

Female part-time
managers

18.7

36

11.3

6.8

24.6

2.5

Figure 4: Comparative referent for part-time managers by gender9Next, the study narrows its focus to female part-time managers and considers the relation
between differences in their family circumstances and their choice of comparative referent.
Specifically, the study investigated how comparative referents differed for those female parttime managers categorized as “with spouse, without children,” “with spouse, with children,”and “single mother.” Figure 5 is a graph of the proportions of comparative referents chosen,
per family circumstances.
The proportion of those who made comparison with regular employees is 25% for “withspouse, without children” and “with spouse, with children,” but over 30% for “single mother.”In other words, a high proportion of single mothers make upward comparisons. The proportionof those who made comparison with part-time managers is highest for “with spouse; withchildren.” The proportion of those who made comparison with part-time workers is no morethan around 15% for “with spouse, with children” and “single mother,” but 25% for “withspouse, without children.” In other words, a high proportion of “with spouse, without children”
make downward comparisons.
60
50
40
30
20
10

Regular employees Part-time manager Part-time workers

With spouse; no children

25

50

25

With spouse; withchildren

25.2

59.5

15.3

Single mother

33.3

52.4

14.3

Figure 5: Comparative referent for female part-time managers
It may be assumed that a common feature shared between male part-time managers andsingle-mother part-time managers (i.e., high proportions who make upward comparison) is
the financial situation of the individuals concerned. They both must earn sufficient income as
the main household earner. It is also expected that many would aspire to become regular
employees if given the opportunity. Thus, they make comparison with regular employees, whohave more stable income and relatively better treatment than they have. However, a highproportion of those who were “female, with spouse, without children” made downward
comparison. These people probably do not need to support household finances to the same
extent as single mothers do. Further, a high proportion of those who were “female, with spouse,
with children” chose to compare with fellow part-time managers. Essentially, the greater theneed to support household finances by oneself, the higher the proportion of upward
comparison; as this need decreases, the proportion of downward comparison increases.
6.

Conclusion
In order to explain the reason why non-regular employees’ motivation is relatively not low
compared with regular employees, this study first demonstrated the levels of motivation in
non-regular employees and then, focusing on “sense of distributive justice” and “choice ofcomparative referent,” conducted the following three investigations: (1) the relation between
10

sense of distributive justice and motivation; (2) the relation between sense of distributive
justice and comparative referent; and (3) the personal attributes that influence the choice ofcomparative referent.
As in previous studies, this study showed that non-regular employees have higher
motivation than regular employees, and it became clear that sense of distributive justiceincreases motivation. Next, the study focused on comparative referents and found that senseof distributive justice tended to decrease as the comparative referent shifted from downward
to upward. Finally, focusing on the personal attributes of non-regular employees, the study
undertook an exploratory investigation into different types of non-regular employees andcomparative referents they choose. Accordingly, it emerged that financial conditions, such aswhether the individual concerned was the main household earner, may influence comparison
choice.
The practical implication of this study is that measures that increase sense of distributive
justice will be effective for increasing non-regular employees’ motivation. Here, non-regular
employees who made comparison with regular employees had lower sense of distributive
justice and lower motivation than non-regular employees who chose other comparativereferents. A decrease in motivation may be caused by the gap between an ideal state andreality, where individuals wish that they themselves were also the same as the referents fortheir upward comparison and that the present situation is different. In such a case, it isdifficult to change the comparative referent, so it is desirable to be able to independently selectan appropriate form of employment, for instance by improving the system for transferringfrom non-regular to regular employment. Additionally, it is important for enterprises to notpromote uniform measures for all non-regular employees, but to comprehend with whom each
non-regular employee is making comparison, and to incur a perception of justice by theemployee.

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12

Appendix :Correlation matrix of variables related to the analysis in this study
Variable

Mean

s.d.

1

1 vagetable and fruits_dummy

.13

.34

2 fish_dummy

.13

.34

2

3

4

5

6

7

8

9

10

3 meet_dummy

.09

.29

-.12 *** -.12 ***

.12

.33

-.14 *** -.15 *** -.12 ***5 in-store bakery_dummy

.01

.1

-.04

6 grocery_dummy

.1

.29

-.13 *** -.13 ***

-.04

-.03

14

15

16

17

19

20

21

22

23

24

25

-.04

.08

.27

-.12 *** -.12 *** -.09 *** -.11 *** -.03-.1 ***.06.24-.1 ***-.1 *** -.08 **-.09 *** -.02-.08 **-.07 **

9 service_dummy

.05

.21

-.09 **-.09 **-.08 **-.02-.07 **-.07 *-.06 *

10 cashier_dummy

.06

.24

-.1 ***-.1 *** -.08 **-.1 *** -.03-.08 **-.08 **-.07 *-.06 *

11 general affairs_dummy

.04

.21

-.08 **-.09 **-.08 **-.02-.07 **-.06 *-.05 *-.05-.06 *

12 age

42.02

11.94

-.07 *-.14 *** -.02-.02

13 gender

1.45

.5

13.11
2.73

-.07 *-.07 *-.09 **

-.01

.05 †

.05 *

-.01

.14 ***.18 ***-.12 *** -.25 *** -.14 ***.12 ***

.06 *

.04

.12 *** -.03

.24 ***.28 ***.23 ***.29 ***

8.79-.06 *-.08 **-.03-.05 †-.05 †.01.0-.06 *

-.01

.04

.05 †

.69 ***

1.94

.01

.06 *

.02

.04

-.09 **-.08 **-.1 ***.04-.02-.28 *** -.27 *** -.21 ***-.4 ***-.01-.62 ***.19 ***

16 regular employee_dummy

.71

.45

.06 *

.13 ***.04.07 **-.1 *** -.07 *-.1 ***.04.01-.31 *** -.29 ***-.61 *** -.03

.89 ***

17 number of relocation transfers

1.84

2.34

.03

.07 *

.0

.02

-.06 †-.09 **

-.02

-.03

-.03

-.14 *** -.15 *** -.11 ***-.37 ***.18 ***.46 ***.38 ***

18 number of job changes (reshuffling)

4.70

5.25

.01

.01

-.02

.02

-.06 *-.04-.04-.12 *** -.04-.15 *** -.15 ***-.39 ***.6 ***.56 ***.42 ***.48 ***

19 monthly overtime hours

19.48

11.55

.07 *

.08 **.04.02-.07 *-.1 **-.05-.15 ***.0-.03-.29 *** -.08 **.28 ***.29 ***.19 **.53.5-.07 *-.05 *-.01-.06 *

.02

-.03

-.01

.02

-.04

.05 †

.03

.26 ***.05 †-.11 *** -.05 †.28 ***

20 with spouse_dummy

18-.1 *** -.12 *** -.03

8 non-foods_dummy

15 qualifications

13.

7 dairy-foods_dummy

number of years of continuous work
since joining the company

12-.15 ***

4 deli_dummy

1411.24 ***-.15 *** -.23 ***.1 ***.35 ***.12 ***.15 *** -.07 *21 with children_dummy

.53

.5

-.07 **-.09 **-.04-.08 **

.02

.02

.04

.01

-.03

.07 **.11 ***.49 ***.18 ***-.08 *** -.23 *** -.18 **.07 *-.14 ***.6 ***

22 with preschool infants_dummy

.11

.31

.04

.01

-.03

-.03

.01

-.05 †

-.02

.04

-.03

-.05 *-.05 *-.23 ***-.21 *** -.14 ***.21 **.19 ***

.1 **

.05

.08 **.31 ***.34 ***

23 job satisfaction

3.12

.94

-.03

-.04

-.02

-.05

.03

.06 *

.0

.07 **

-.02

.02

.03

.16 ***.05 **.09 **-.05 *-.09 **.0-.03-.08 **.08 **.08 **-.03

24 distributive justice

3.04

.81

-.02

.0

-.04

.02

.01

-.02

-.03

.05 *

.05

-.02

.01

.03 ***

.04 †

.05

.06 *

.04

-.01

-.02

-.09 **

.01

.01

.0

.31 ***

25 affective commitment

3.29

.84

-.03

-.04

-.06 *

-.01

.02

.02

.01

.07 **

.0

.03

.04

.15 ***.03.07 **

.01

-.04

.01

.0

-.03

.12 ***.12 ***.02.49 ***.34 ***

26 motivation

3.19

.86

-.02

-.05

-.05

-.06 *

.04

.04

.04

.09 **

-.03

.03

.06 *

.19 ***.06 *.09 **-.05 †-.1 *** -.01

-.02

-.04

.16 ***.16 ***.01.54 ***.29 ***.8 ****** Significant at the 0.1% level** Significant at the 1% level* Significant at the 5% level† Significant at the 10% level[2017.3.13 1231]
13