Data-based decision making has been developing as one of the key fields in education over the last decades. Numerous studies show effectiveness of management based on data, rather than experience and intuition (Marsh, Pane & Hamilton, 2006, Schildkamp, 2019). Many of the problems schools face do not have an obvious solution. While addressing the issue with no delay may seem effective, acting without the data is often ineffective and can lead to the emergence of other problems as a consequence. For instance, a school opens a new direction of additional education without a preliminary analysis of the stakeholders' request, thereby wasting resources, since the request may be different or it can be addressed by an offer from the school's competitors. Thus, data-driven decision making allows to reduce the number of managerial mistakes resulting from unreasonable and not-informed decisions made following the intuition. 

Today, new tools are being developed that can help school management teams collect and store data, as well as visualize and analyze this data. All this contributes to the usage of data in making managerial decisions. What is more, it is expected that a principal of a school being a leader should have particular skills in data-based management and should convey the need and advantages of its usage to make informed decisions. It is crucial to encourage the use of data, data collection not as an activity that is aimed at meeting accountability requirements but as a continuous process which can be used to develop school development strategy, for school improvement (Schildkamp, 2019).

In this way, while the prevailing necessity of evidence-based decision making has been discussed and accepted widely, there is a vast array of studies on the topic in Russia and all over the world. Our studies are focusing on school management practices of data-based decision making and management of the school. We carried out a research in one of the biggest and well-developed megacities where the majority of schools are large school complexes comprising up to 18 buildings which are often located in different parts of the city, assuming that management of a big school complex is impossible without data and requires informed decisions from school management team.

The key research questions:

- What data-driven management practices have developed in schools of a Russian megacity? What management tasks do school management teams solve based on data? What situations do they need data for?

- What obstacles and difficulties do school managers face when using data in school management?

Mix methods (quantitative and qualitative approach) were used to carry out the studies. Quantitative approach was used to shed light on the data-driven decision-making and management practices of school leadership teams. A questionnaire was developed in several stages: - we analyzed existing theoretical frameworks, taxonomies of data in educational environments (Bernhardt, 2013; Celio and Harvey, 2005; Marsh et al.al, 2006) and developed our conceptual framework that laid as the basis of our questionnaire and interview guide. - We developed an interview guide to conduct interviews with school management teams to get qualitative data on management practices which can be used in the development of the questionnaire. Thus, the questionnaire was created taking into account the specifics of the megacity's schools. The guide comprised blocks: contingent (students, family), personnel management, educational program, management system, self-assessment. - Development of the questionnaire based on the interview guide, transcripts of interviews and already existing questionnaires developed by the Institute of Education of NRU HSE. The wording of the questions went through several iterations of adjustments as a result of expert discussions. - Testing the questionnaire on a small sample of school leadership teams. - final revision of the questionnaire and its launch. The survey was sent to all the schools of the Megacity. In this way, school leadership teams voluntarily decided to participate in the study. We guaranteed confidentiality information. 453 members of school management teams took part in the survey: 134 principals, 271 deputies and 46 others (teachers, methodists etc.). The sample comprised schools of different sizes from small school (less than 40 classes) to big school complexes 83% (more than 40 classes). Qualitative approach was used to carry out interviews with school management teams (principals and their deputies). 25 respondents from 8 educational organizations were interviewed (3-4 from each school). The sample was formed based on the results of a quantitative study from the two main group of schools presented in the survey: - schools with high enrollment rate, which have a data collection plan, rely on data in management; - schools with a relatively low enrollment rate (less than 40 classes per school) that rely on data when managing the school, but they do not have a data collection plan. Interviews were crucial for the interpretation of the data collected via survey. They allowed to ger a more in-depth information about the data-driven management practices of school management teams.

The studies revealed that data-based decision making and management has become an essential part of a school management team work. 94% of the sample makes data-driven decisions when solving 8 -18 problems. School leaders actively use platforms developed by the Department of Education to get the data. The most common category for data-collection is the data related to students and their families. Nevertheless, members of management teams prefer to independently organise collection and analysis of the data. They independently develop tools/surveys for data-collection (80%) or use approaches/methods that are available online (44%). Data-based decision-making and management has become a systematic story for leadership teams of larger schools (more than 40 classes) as they have a greater need for data, such schools are more likely to have a data-collection plan (41% of schools). Data related to teachers was stated as a valuable source and one of the demanded types of information for making decisions but at the same time school management teams lack it the most too.

Bernhardt, V. L. (2013). Using Data to Improve Student Learning in School Districts: To Improve Student Learning In School Districts. Routledge. Celio, M. B., & Harvey, J. (2005). Buried Treasure: Developing A Management Guide From Mountains of School Data. Center on Reinventing Public Education. Marsh, J. A., J. F. Pane, and L. S. Hamilton. 2006. Making Sense of Data-Driven Decision Making in Education: Evidence from Recent RAND Research. Santa Monica, CA: RAND Corporation Schildkamp, K. (2019). Data-based decision-making for school improvement: Research insights and gaps. Educational research, 61(3), 257-273.