| Popis: |
In this study, we first discuss the issues of treatment of seasonal items in consumer price indices (CPI), strong seasonality and unpredictable volatility. Later we examine the effect of selected seasonal treatment methods on the volatility of Laspeyres-type CPI for the first time using a unique data set of fresh fruits and vegetables prices from 2007 to 2011. Based on combination of treatment methods we calculate 720 different fresh fruits and vegetables price indices. Results suggest that using 2 or 3 month price averages reduces the monthly volatility of strongly seasonal products by 15 and 23 percent, respectively, in comparison to using one month averages. Also, using fixed weights yields 18 percent lower volatility than using variable weights. The other categories of base price selection, imputation of missing prices and treatment of extreme prices/trimming have mixed yet minor effects on volatility. |
