Efficiency trends within windows, on individual hospital basis, are shown in Table 4 which has been constructed in the following way: There are four columns per group corresponding to the four windows. Three symbols “↗”, “↘” and “↔”, are used to denote improvement, deterioration or steadiness of a hospital’s efficiency respectively, when going from the first to the second year within the same window. In addition, the symbol “+” is used in conjunction with these three symbols to denote a fully efficient unit in the implied year on the left or right hand side of the arrow. It is clear that only the three combinations “↗+”, “+↘”, and “+↔+” may arise. The first one, “↗+”, will be used when efficiency improvement starts from a non-efficient unit and leads to a fully efficient unit. Symmetrically, the second one, “+↘”, will be used when efficiency deterioration starts from a fully efficient unit and leads to a non-efficient unit. Finally, the third one, “+↔+”, will be used to denote the transition from a fully efficient unit to an also fully efficient unit. An extra summary column to the right of the four window-specific columns (labeled “inter-temporal trend”) is used in order to designate a constant inter-temporal (all-windows) behavior of a unit whenever there is one. Thus, if the same trend symbol appears for a hospital in all four windows the corresponding symbol (↗, ↘, or ↔) is placed in this summary column. In addition, the extra symbol “√” is placed in this column whenever a hospital manages to be fully efficient in at least one year within every window. Therefore, it is evident that the combined presence of the “√” together with the symbol ↔ (i.e. ↔√) indicates a fully efficient hospital throughout all years within all windows. Similarly, the presence of symbol “√” either sole or accompanying the symbols ↗ and ↘, indicates an (inter-temporal) almost fully efficient unit which we shall call a “semi-efficient” unit. Finally, at the bottom of the table, a summary of column totals shows the number of occurrences of each trend symbol. It is worth noting that the total number of occurrences of the “+” symbol on the left (or right) side of a trend arrow coincides with the total number of fully efficient hospitals in the year implied on the corresponding side of the arrow. For example, as can be seen in summary section of group B in Table 4, the symbol “+” appears 14 times on the right of trend arrows (9 x “↗+” and 5 x “+↔+”) in window (column) 2010–11. There are, therefore, 14 VRS fully efficient hospitals (within window 2010–11) in the year which is implied on the right of the particular trend arrow which, in this case, is 2011. Similarly, there are 7 (5 x “+↔+” and 2 x “+↘”) fully efficient hospitals in year 2010 within window 2010–11. Furthermore, it is evident that 5 hospitals (5 x “+↔+”) managed to be fully efficient in both years within window 2010–11.