Statistical Thinking in quality improvement: use, difficulties and benefits of its implantation in industries of the Brazilian State of São Paulo

Toledo, Jose Carlos de; Lizarelli, Fabiane Letícia; Santos, Adriana Barbosa dos; Ishizaka, Artur

doi:10.1590/0103-6513.20180062

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Research Article • Prod. 28 • 2018 • https://doi.org/10.1590/0103-6513.20180062 linkcopy

Statistical Thinking in quality improvement: use, difficulties and benefits of its implantation in industries of the Brazilian State of São Paulo

Authorship SCIMAGO INSTITUTIONS RANKINGS

Paper aims Identify the use of statistical thinking and techniques and their main difficulties and benefits in the Brazilian State of São Paulo industries.

Originality There are few empirical studies on the application of the statistical thinking and techniques which study their difficulties of implementation and their benefits in manufacturing companies.

Research method A web survey of a sample of 243 manufacturing companies.

Main findings The companies, in general, use some statistical principles and basic techniques for process control and improvement, however, companies that use principles and techniques more consistently have greater operational and team benefits. The main difficulties are associated to lack of culture and knowledge.

Implications for theory and practice The statistical application enables effective processes improvements and it is associated with motivation for further improvements, consolidation of improvement programs and culture of quality. This finding suggests managerial implications such as to plan actions to deploy and disseminate the culture of statistical thinking in an evolutionary way, training and support for use and to overcome barriers.

Keywords
Statistical techniques; Statistical approach; Improvement programs; Perceived benefits

STk principles	Authors
Continuous training and dissemination of STk principles	Snee (1990) , Abraham (2005)
Top management commitment to the STk principles implementation	Abraham (2005)
Interconnected processes vision	Snee (1990) , Makrymichalos et al. (2005) , Hoerl & Snee (2012)
Understanding of the need to quantify and reduce variability	Snee (1990) , Makrymichalos et al. (2005) , Hoerl & Snee (2012)
Importance of the data that is going to be used in the analysis (data quality)	Wild & Pfannkuch (1999) , Makrymichalos et al. (2005)
Focus on the data and its measurement	Hoerl & Snee (2009)
Decision making based on facts and data	Hoerl & Snee (2012)
Acknowledge cause-effect relations to analyze variability problems	Makrymichalos et al. (2005)

Barriers categories	Barriers
Managerial view	▪ Statistics is applied, especially in operational level, being little used in managerial decision making.
	▪ Lack of support and involvement of top management on promoting and applying STk and STe.
	▪ Belief that STe are short-term initiatives, not capable of delivering sustainable improvements.
	▪ In general, managers cannot distinguish common and special causes of variance in key business processes.
	▪ Managers and engineers have difficulty in approach processes focusing on variability.
Education and technical qualification	▪ Lack of appropriate statistical and technical knowledge by managers and engineers.
Education and technical qualification	▪ Discrepancy between the theoretical knowledge about STe and the organizations’ needs.

Characteristics	Results
Importance of quality for the competitive strategy (n=243) *
Low	8 (2.9%)
Medium	53 (21.9%)
High	182 (75.2%)
Improvement Programs	Do not have	< 5 years	> 5 years
Kaizen (n=220)	84 (38.2%)	71 (32.3%)	65 (29.5%)
Day-to-day Improvement Initiatives (n=233)	21 (9.0%)	89 (38.2%)	123 (52.8%)
Suggestion Box (n=222)	62 (27.9%)	68 (30.6%)	92 (41.5%)
Six Sigma (n=219)	104 (47.5%)	61 (27.8%)	54 (24.7%)
Lean manufacturing (n=213)	69 (32.4%)	76 (35.7%)	68 (31.9%)
Lean sigma (n=203)	140 (69.0%)	37 (18.2%)	26 (12.8%)
TPM (n=203)	92 (45.3%)	47 (23.2%)	64 (31.5%)
TQM (n=204)	124 (60.8%)	32 (15.7%)	48 (23.5%)
5S (n=233)	18 (7.7%)	84 (36.1%)	131 (56.2%)

Type	Results
Systematic actions towards diffusion and training and application of STk and STe principles (n=240)
Present for 5 or more years	42 (17.5%)
Present for less than 5 years	64 (26.7%)
Not present	134 (55.8%)
Investments in training and application of STk and STe in the last 5 years (n=237)
No increase	108 (45.6%)
Little increase	90 (37.9%)
Significant increase	39 (16.5%)

Topics related to STk principles in the organization	High Frequency ^*
1. Continuous training about STk principles	10.7%
2. Top management support for the application of STk principles	32.9%
3. The application of STk principles is disseminated and fostered	13.7%
4. The main process is under statistical control	27.6%
5. Process vision is consolidated among supervisors and managers	50.2%
6. Process vision is consolidated for operators	18.9%
7. It is understood that variability is present in all processes	38.2%
8. It is understood that there is a need to quantify variability	37.4%
9. Data collection is questioned by managers and supervisors	32.6%
10. The application of measurement system analysis	21.8%
11. Decision making based on facts and data	40.7%
12. Perform analyses considering cause-effect relations	55.6%
13. Awareness about the critical role of variability reduction for the manufacturing performance	60.5%

Sector groups	Systematic application of STk and STe ^*		P value (Fisher’s exact test)
Sector groups	Group NA	Group A	P value (Fisher’s exact test)
G1	53 (40.1%)	79 (59.9%)	0.020
G2	62 (55.8%)	49 (44.1%)	0.020
Total	115 (47.3%)	128 (52.7%)

Motives	Percentage of agreement
Lack of a suitable culture for the application of STk/STe	66%
Applies sporadically, due to external demands and other company priorities	57%
Lack of internal knowledge that supports the systematic application	57%
The level of training and knowledge does not allow the application	28%
There is a predominant view that the application of STk/STe is complex	26%
There isn’t a belief on the potential of the application of STk/STe	13%
We do not feel the need for a systematic application	13%
Managers see STk/STe as a “firefight” tool only	10%
Managers believe that STk and STe can only be applied in operational level, and they are not important for managerial and strategical issues	3%

Indicator	Positive responses ^*		P Value ^**
Indicator	Group A (n=128)	Group NA (n=115)	P Value ^**
Objective (Process Performance)
1. Reduction of the index of internally identified non-conformities	41.4%	24.4%	0.0063
2. Reduction of customer index complaints/returns	43.8%	30.4%	0.0346
3. Increased level of customer satisfaction	46.1%	33.0%	0.0489
4. Reduction in non-quality costs	39.8%	33.9%	0.3546
5. Reduction of production cycle (time)	32.8%	33.9%	0.8920
6. Reduced production costs	29.7%	26.1%	0.5689
7. Increased productivity	38.3%	40.0%	0.7938
8. Improvement of process capability indices (CPk)	35.9%	30.4%	0.4141
Perceived satisfaction with the application of STk and STe
1. Manager satisfaction level	39.1%	20.9%	0.0022
2. Operational level employee motivation in the application of STk and STe	18.8%	13.9%	0.3868
3. Increased understanding of the process and problem-solving ability	29.7%	22.6%	0.2441
4. Contribution of the use of STk and STe to consolidate improvement programs	39.1%	28.7%	0.1044
5. Variability reduction, process stability and capacity improvement	33.6%	25.2%	0.1623
6. Increased concern about measuring and understanding the variability of processes and their causes	46.1%	37.4%	0.1937
7. Change in organizational culture in favor of quality	41.4%	27.0%	0.0216

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Associação Brasileira de Engenharia de Produção CNPJ: 30.115.422/0001-73, Avenida Cassiano Ricardo, Nº 601, Residencial Aquarius, CEP: 12.246-870, http://portal.abepro.org.br/ - São José dos Campos - SP - Brazil
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[1] Source: Bjerke & Hersleth (2001) ; Makrymichalos et al. (2005) ; Bisgaard et al. (2008) ; Abraham (2005) ; Firka (2011) ; Ahmed & Hassan (2003) ; Grigg & Walls (2007) ; Montgomery (2010) ; Coleman (2013) .