*4.1.1. The measurement of tourism activity in studies of economic growth*

Tourism activity has been measured in various ways to be able to make econometric estimates that serve as the basis for the study of the relationship of that activity with economic growth. There are researchers who use the income obtained by international tourism as a measure of tourism activity [62,65,80–83]. Others use the number of non-resident tourists who visit the country [84–86]. The choice of indicator is of special importance, because, as stated in [79], the way in which tourism activity is evaluated will also affect its elasticity of productivity. Thus, if tourism activity is measured by the income that it generates, then the elasticity will tend to be greater than if it is measured based on visitor numbers.

Additionally, other studies use the people registered in hotels [87], the number of overnight stays of foreigners in hotels [88], the income obtained by the hotel industry [89], the sales income in hotels and restaurants [90], or the cost in tourism [91]. All these ways of measuring tourism activity have the commonality that they are measured from the point of view of demand, which supposes that economic growth is linked to demand. A perspective that has been criticised by several economists, as it does not allow the contribution of tourism to economic growth to be suitably demarcated [92].

In this regard, new approaches [93] have recently appeared that use the TTCI to measure the contribution of tourism activity to economic growth, analysing if this activity stimulates economic growth in the most competitive destinations. However, this study does not consider the role that other productive factors, such as capital investments, have in economic growth.
