Introduction

Workplace bullying is increasingly recognized as a serious problem within the work environment. A weighted prevalence rate of bullying in the meta-analysis was reported 11.9% when the victims was defined as experiencing at least negative acts weekly or more within six months. In Japan, the prevalence of workplace bullying was reported 9.0% among 1,624 local government workers. Previous studies showed workplace bullying have various negative impacts both on individuals and organizations. For example, workplace bullying was positively associated various health outcomes such as psychological distress, depression, and cardiovascular disease. It has also been related to rises in negligence, staff turnover, and cases of sick leave.

Although bullying is reported at all organizational levels, managers are reported to be the most frequent perpetrators from the point of view of targets. Zapf et al. analyzed data of 6,783 victims and reported with the weighed percentages that 65.4% were bullied by supervisors, 39.4% were bullied by colleagues, and 9.7% were bullied by subordinates. Analyzing about 800 case studies of bullying, Leymann found consistent patterns of poorly organized work conditions and 'helpless' or 'uninterested' leadership behavior in all cases, concluding that organizational factors relating to the organization of work and the quality of leadership were a major cause of bullying at work. These organizational characteristics of work and workplace are considered to have an influence on bullying at work, both directly and indirectly through creating a stressful work climate.

Hauge et al. found laissez-faire leadership behavior as one of the strongest predictors of bullying and recent studies put focus on this passive and indirect leadership style. Previous study argued that a lack of adequate leadership, which is the case with laissez-faire leadership, might create frustration and stress within a workgroup, which might also result in interpersonal tensions and escalated levels of conflict. Skogstad et al. reported that experiencing laissez-faire leadership by one's immediate supervisor was associated with high levels of role conflict and role ambiguity and also with increased conflict levels with coworkers, and in their path analysis these three work stressors mediated the association between laissez-faire leadership and bullying at work, as well as a direct effect of laissez-faire leadership on workplace bullying. However, these previous studies are all cross-sectional, which could not exclude a possibility that subordinates who experienced workplace bullying might be more likely to rate their supervisor's leadership negatively, which is called negative halo effect.

On the other hand, there are other leadership styles that positively influence subordinates, i.e., transformational and transactional leadership. Both leaderships have positive relationships with subordinates' job satisfaction or organizational effectiveness. Although there are a few studies that found transformational and transactional leadership was negatively associated with workplace bullying, results were repugnant. Additionally, these studies were also cross-sectional. The aim of this study is therefore to investigate the prospective association between various leadership styles of one's immediate supervisor at baseline and workplace bullying at follow-up, using six-month follow-up data of Japanese civil servants at a local government.

Methods

Baseline survey was conducted in September 2011 and follow-up was in March 2012. All data were collected using a self-administered questionnaire. At baseline, 991 questionnaires ware returned (response rate, 47.9%) and a total 404 follow-up questionnaires were returned in sealed envelopes at follow-up (follow-up rate, 40.8%). After excluding 87 workers who had at least one missing response for any of the variables relevant to this study, responses collected from 317 workers were analyzed.

Workplace bullying was measured by the Japanese version of Negative Acts Questionnaire-Revised (NAQ-R). Exposure to bullying was defined as experiencing at least one negative act on a weekly or daily basis for the previous six months, according to the criteria put forward by Leymann. All supervisor leadership styles were measured by the Japanese version of Multifactor Leadership Questionnaire (MLQ). MLQ examine six factors of leadership: three transformational leaderships (charisma/inspirational, intellectual stimulation, and individual consideration), two transactional leaderships (contingent reward and active management-by-exception), and passive/avoidant (or laissez-faire) leadership. A total score for each factor was calculated by averaging items scores. Then, the participants were divided into tertiles (high, moderate, and low) in terms of their scores for leadership styles at baseline respectively. Demographic variables included gender, age, education, marital status, and chronic condition; occupational variables included occupation, employment contract, and shift work at baseline. Life events in the past six months were defined as experiencing at least one life event related to work, individual, or family.

A series of multiple logistic regression analyses were utilized among a subsample (n=270) that excluded those who experienced bullying at baseline to estimate the odds ratios (ORs) of workplace bullying at follow-up for each leadership group. A trend test was also conducted to examine the dose-response relationship of each categorized leadership style at baseline with workplace bullying at follow-up. In addition to these analyses, another multiple logistic regression analyses also conducted among whole respondents (n=317) and a subsample (n=258) that excluded managers at baseline.

Results

The prevalence of bullying at work was 14.8% at baseline and 15.1% at follow-up in the present sample. Twenty-five participants were newly exposed to workplace bullying at follow-up.

Among respondents who did not experience workplace bullying at baseline (n=270), low individual consideration leadership (OR, 3.38 [95%CI, 1.09-10.5]; p for trend = 0.033) and high passive avoidant leadership group (OR, 4.28 [95%CI, 1.29-14.2]; p for trend = 0.018) was more likely to be associated with workplace bullying at follow-up compared to low group after adjusting for demographic and occupational characteristics and life events during the follow-up. After all variables were simultaneously entered in the model, only passive avoidant leadership group was significantly and positively associated with workplace bullying at follow-up (OR, 3.74 [95%CI, 0.92-15.3], p for trend = 0.042). Among whole sample (n=317), compared to high group, low charisma/inspirational leadership group (OR, 2.81 [95%CI, 1.04-7.57]; p for trend = 0.037), low individual consideration leadership group (OR, 3.13 [95%CI, 1.22-8.04]; p for trend = 0.013), and low contingent reward leadership group (OR, 3.71 [95%CI, 1.40-9.80]; p for trend = 0.007) were significantly more likely to be associated with exposure to bullying at follow-up, while high passive avoidant leadership group (OR, 2.82 [95%CI, 1.11-7.19]; p for trend = 0.031) was significantly more likely to be associated with bullying at follow-up compared to low group after adjusting for demographic characteristics, occupational characteristics, life events during follow-up, and exposure to bullying at baseline. Among respondents who were non-managers at baseline (n=258), the analysis showed similar results as a subsample (n=270) and whole sample, respectively.

Discussion

In the present study, high passive/avoidant (laissez-faire) leadership and low individual consideration leadership was significantly and positively associated with a new case of workplace bullying. Further analyses among whole respondents also found that passive/avoidant leadership was significantly and positively associated with exposure to workplace bullying at follow-up, after adjusting for demographic and occupational characteristics at baseline, life events during the follow-up, and exposure to workplace bullying at baseline. All transformational leadership, i.e. charisma/inspirational, intellectual stimulation leadership, and individual consideration leadership, were significantly and negatively associated with exposure to bullying at follow-up after adjusting for demographic and occupational characteristics at baseline, life events during the follow-up, and exposure to bullying at baseline. This study found various leadership types were positively or negatively associated with exposure to workplace bullying, however, passive/avoidant leadership seemed most strongly associated with it, since only passive/avoidant leadership was significantly and positively associated with a new case of workplace bullying even after all variables were simultaneously entered in the model. From this result, other leadership types might work on exposure to workplace bullying complementary. These findings are consistent with previous cross-sectional studies on the association between laissez-faire leadership, and workplace bullying. The present study expanded the previous cross-sectional evidences by using a longitudinal study design as well as well-established scales of leadership styles and workplace bullying. Additionally, the present study showed that transformational leadership might be associated with workplace bullying.

In this sample, 14.8% at baseline and 15.1% at follow-up experienced workplace bullying. These prevalence rates are higher compared to previously reported rates (9.0% to11.9%) but similar with those among Japanese workers (14.7% to 15.9%), which used same definition. Although the prevalence in this study was not so much higher than previous research in Japan, there is a possibility that the prevalence was higher than usual condition because the city the respondents worked was affected by 3.11 Great East Japan Earthquake. Previous studies suggested stressful and poorly organized work environments may give rise to conditions resulting in bullying.

Some limitations of the present study should be considered. First, the baseline response rate and follow-up rate was moderate. Participants who had an experience of workplace bullying or felt frustration for their supervisor leadership may have been more likely to respond to the survey, which could result in overestimation of the association of leadership and workplace bullying. On the other hand, there were a certain number of respondents who failed to complete the questionnaire and were excluded, in addition to those who did not respond to the follow-up survey, which may lead selection bias. Third, the present sample came from only one city in Japan and all participants were civil servants so that the generalization of the findings should be done carefully. Fourth, all data were collected self-report questionnaires, which may result in common method bias. Furthermore, whether the respondents have experienced actual bullying behavior or not was not clear in a precise sense because exposure to workplace bullying was measured by self-report. In the present study, it is possible that leadership styles were associated with worker perception, since worker perception on workplace bullying cannot be totally excluded from the assessment. Further research on leadership styles and workplace bullying needs to include a group level analysis. Finally, although various leadership styles have been investigated as predictor of bullying in this study, there are other important organizational factors that may have influenced exposure to workplace bullying. To fully understand organizational predictors of bullying, future studies in this area should also investigate organizational factors such as role conflict and role ambiguity, as well as other types of leadership behaviors.

Conclusions

To our knowledge, the present study first explored the association between supervisor leadership styles and workplace bullying using a longitudinal study design. The present study adds to the existing literature by showing that passive/avoidant (laissez-faire) was a strongest predictor of the new exposure to workplace bullying and low individual consideration leadership also predict the new exposure to workplace bullying. Additionally, transformational leadership may prevent to enlarge workplace bullying. These findings might have important implications for the prevention of workplace bullying. For instance, it may be useful to provide an educational intervention program for managers and supervisors and tell them that doing nothing in terms of the leadership can be most harmful while positive and active relationships could prevent or enlarge conflicts between workers. However, a further study is needed to fully understand the relationships between organizational factors, including various leadership styles, and the occurrence of workplace bullying in both public and private sectors as well as across countries.

本研究は、関東地方の市に勤務する日本人公務員を対象に、直属上司のリーダーシップ形態と職場のいじめ・ハラスメントへの曝露との関連を明らかにするため、半年間の追跡調査を行い、2時点での質問紙調査を行うことで解析を試みたものであり、下記の結果を得ている。

1.職場のいじめを受けている割合(実態)はベースライン時で14.8%、フォローアップ時には15.1%であった。本調査対象者が勤務する市は東日本大震災の被災地域であり、ストレスフルな状況から本来よりも割合が高くなっている可能性があるものの、この割合は、これまでの日本における先行研究(9.0%から15.9%)と同程度であると考えられた。

2.ベースライン時にいじめ曝露を受けていない回答者(270名)を対象とした多重ロジスティック回帰分析の結果、ベースライン時の個人属性・職業特性、過去半年間のライフイベントを調整後においても、消極回避型リーダーシップ度の高いことと個別的配慮型リーダーシップ度が低いことは、新規いじめ曝露と関連することが明らかになった。同じくベースライン時にいじめ曝露を受けていない回答者を対象として、追加で他のリーダーシップ形態を含む全変数を投入するモデルを実施したところ、新規いじめ曝露との有意な関連が残ったのは消極回避型リーダーシップ形態のみであった。消極回避型リーダーシップについては、先行研究で指摘されている通りの結果が得られ、また最後まで有意に関連が残ったのは消極回避型リーダーシップのみであることから、いじめの強い予測因子は消極回避型リーダーシップであることが示された。個別配慮の少ない状況は、消極回避型リーダーシップ形態がある状況と似ていると考えられる。

3.回答者全員(317名)を対象とした多重ロジスティック回帰分析の結果、ベースライン時の個人属性・職業特性、過去半年間のライフイベントを調整後においても、消極回避型、個別配慮型リーダーシップに加えて、カリスマ/動機付けリーダーシップ度の低いことと、業績主義の報酬型リーダーシップ度の低いこともフォローアップ時の職場のいじめ曝露と関連することが明らかになった。なお積極的な例外管理リーダーシップ度については、どのモデルにおいても職場のいじめ曝露との間に有意な関連を確認することができなかった。これにより、変革型と呼ばれるリーダーシップ形態があることは、いじめの予防因子になる可能性が示唆された。

4.上記2種類の解析において、それぞれベースライン時に管理職でなかった回答者(258名)を対象に解析を行ったが、ほとんど結果は変わらなかった。これにより、本解析のロバストネスが確認できたと考えられた。

以上、本論文は直属上司のリーダーシップ形態と職場のいじめ・ハラスメントへの曝露との関連を縦断的に検討した初めての研究であり、先行の横断研究で指摘されている消極回避型リーダーシップ形態がいじめの強い予測因子となると考えられること、さらに先行研究ではほとんど明らかになっていなかった予防因子として、上司の個別配慮型リーダーシップの高さ、カリスマ/動機付けリーダーシップの高さ、業績主義の報酬型リーダーシップ形態の高さが可能性として挙げられ、職場のいじめ・ハラスメント予防の取り組みと上司の効果的マネジメントの解明に重要な貢献をなすと考えられ、学位の授与に値するものと考えられる。