One of the main objectives of implementing Quality Management Systems (QMS) is to improve management and systematisation of procedures (for planning, organisation, control, evaluation and continuous improvement), as well as performance and satisfaction of its members (Roque González, Guerra Bretaña, & Escobar, 2016; AENOR, 2015). Although implementation of these QMS in organisations has increased worldwide in recent decades, assessment of their impact is not common. Most studies conducted on the application of these plans merely evaluate immediate results, generally related to development of the system or the satisfaction generated (Fernández-Díaz, Rodríguez-Mantilla & Jover-Olmeda, 2017). However, it is important to question to what extent has the time spent and effort devoted to the design and implementation of these programmes actually led to substantial changes that are sustainable in the organisation (in relation to staff attitude, work styles, climate, planning, etc.). In other words, research is necessary to understand the real impact that the implementation of a QMS has on organisations (Torres, Vázquez, & Sánchez, 2017; Fernández-Díaz, Rodríguez Mantilla & Fontana Abad, 2016; Lasida, Isola, & Sarasola, 2016).

Service organisations are increasingly using these systems to enhance their competitiveness and customer satisfaction (AENOR, 2015). In the field of education, there is a growing interest in the evaluation of these programmes, especially with relation to processes to certify organisations (Cueto & Díaz, 2013; Triviño, Sirham, Moore & Montero, 2011; Ponce, 2010; Zapata & Tejada, 2009), although interest is also increasing in the impact which implementation of QMS has on several school areas or dimensions.

The specialised literature highlights some key areas for assessing this impact, including Leadership and Engagement of the Management Team, the school's Communication System (vertical and horizontal), Climate, optimisation of time and resources, procedure efficiency,  Satisfaction of the education community, Learning Process or External Relations and bonds between the school and society, among others (Fernández-Díaz et al., 2016; AENOR, 2015; Rodríguez Mantilla & Fernández Díaz, 2015; Egido Gálvez, Fernández Cruz & Fernández Díaz, 2016; Lorenzo, 2011). Yet one of the major dimensions is the school's Management system, particularly in relation to the planning culture (systematisation of work procedures, preparation of efficient and useful systems for management and recording of documents, performance evaluation and staff satisfaction, etc.) (Rodríguez-Mantilla & Fernández-Díaz, 2017; Rodríguez-Mantilla & Fernández-Díaz, 2013) and to the Support and Recognition Policy, a key factor for organisational engagement and improvement of teaching quality in schools (Ojeda, Talavera, & Berrelleza, 2016; Talavera Ortega, & Gavidia Catalán, 2013).

Therefore, the main objective of this study was to evaluate the impact which ISO 9001 Standards have had on the dimensions Management and Planning and to compare the views of teachers and heads on said impact, in schools with at least 3 years of implementation. Likewise, we aimed to analyse the different assessments of teachers and heads based on school Ownership and Size, Number of years of implementation and type of Financial aid received for implementation.

The design used for this study was non-experimental, exploratory, along the lines of ex-post-facto studies. We selected schools where ISO 9001 Standards have been in place for at least 3 years, and teachers and heads who had been working at the school for at least 3 years. The sample obtained had 2,185 subjects (86.2% teachers and 13.8% heads) belonging to 85 Spanish schools. 9.1% of the schools were public, 80.3% private with state subsidies and 9.2% private. 39.5% of the sample was made up of small schools (less than 500 students), 37% were medium-sized (between 500 and 1,000 students) and 23.5% were large schools (more than 1,000 students). As for the Number of years of implementation of QMS in the schools, 6.2% had applied it for 3-5 years, 22.2% for 6-8 years, 36.5% between 9 and 11 years and 35% for more than 11 years. 53.8% of the schools received internal aid to implement the ISO 9001 Standards, 11.8% external aid and 34.4% received none at all. To measure the impact which ISO 9001 Standards have had, we used a questionnaire developed "ad hoc", in which subjects answered 25 items in a Likert-type scale from 0 to 4, evaluating improvement of the planning procedures, usefulness of meetings, efficiency of institutional document reviews, recognition of achievements and use of incentives. The tool's reliability analysis showed excellent results (Cronbach's alpha > .96). To secure subject participation, we arranged an initial interview with the school Headmasters, where we explained the study objectives and the procedure. To administer the questionnaires, members of the research team visited the schools on the appointed dates, ensuring complete anonymity and confidentiality of the assessments and results. To process the data we used SPSS 24, conducting descriptive and differential studies overall and for each item (with a significance level of 0.01, applying ANOVA and calculating the size of effect with eta squared) of the teacher and head assessments based on school Size, Ownership, Number of years of QMS Implementation and Type of aid received for implementation.

Implementation of ISO 9001 Standards had a medium-high impact on the Management and Planning system, with significant improvements in the "school's general planning system", development of "Subject Timetables" and usefulness of institutional document reviews. When we compared the assessments of heads and teachers of the impact perceived, we found that heads gave it a higher value, especially in the improvement of the "school's general planning system", development of "Subject Timetables", arrangement of "meetings” and design of Annual Plan, "study of staff expectations", "analysis of complaints and suggestions received from staff", use of “staff satisfaction evaluations" and "recognition of achievement of significant objectives by staff". The differential studies conducted overall show that in private schools with state subsidies there was a greater impact and teacher and head assessments were more balanced. Small schools had a higher impact compared to large ones, and heads from all school sizes gave a higher score to the impact. Schools with 9-11 years of implementation had higher impact levels than those with 3-8 years. Likewise, we found that the level of impact perceived by heads on the Management and Planning system was higher (especially after the sixth year) than that perceived by teachers. Schools which received internal financial aid or no aid at all for implementation of QMS, presented higher impact levels than those that received external aid, the latter being the ones where the impact perceived by heads was highest in both dimensions.

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