A method for analysis of the dynamics of macroeconomic indicators based on the model of a piecewise trend for economies of unstable growth is proposed. The relevance of the article is supported by the absence of adequate mathematical models and the inadequacy of traditional continuous models to describe the features of economic dynamics of this type. Its application is demonstrated on the examples of Ukraine, Greece and Italy in comparison with stable developing countries of Eastern Europe - the Czech Republic, Slovakia and Poland. In the process of approbation new indices of instability based on this model have been developed. A higher degree of conformity of the proposed model is proved in comparison with traditional continuous models not only for countries with signs of unstable economic dynamics, but also for some countries with stable economies. During approbation, a new index of instability of growth was developed based on this piecewise linear trend model. The indices of instability of growth were calculated for 43 European countries for the period from 1989 to 2019 and their rating was built.
JEL Classification: E27, D61, G17