English Abstract: Every field of people's conscientious act require making corresponding decisions. Since making right and timely decisions requires certain information, that can also be applied for making decisions in tourism business. Tourism is a heterogeneous activity, which create numerous...

For proper valuation of risk to which the portfolio of financial assets is exposed, it is necessary to forecast the second moments of financial time series, that is variabilities. The empirical investigations show that financia time series are heteroskedastic, i.e. their volatility is not...