QlikView 11 for Developers chapter 10: Ave load factor per Route per Airlines table

[happyjoshua777]

Hello,

I was not clear about the author's remark on p. 352, namely, "for as the Average Load Factor per Route per Airline value is not the same as the Load Factor per Airline value ". So for comparison's sake I put together a Straight Table with the following expressions:

Average Load Factor per Route

Avg(Aggr($(eLoadFactor), Airline, [From - To Airport ID]))

Airline's Global Load Factor

$(eLoadFactor)

Note: (Sum ([# Transported Passengers]) / Sum ([# Available Seats]))  is the Definition of eLoadFactor variable

Average Load Factor per Airline only

Avg(Aggr($(eLoadFactor), Airline))

See the following results in results_Air-India.png which displays Totals and Air-India

For the two rows of National_Air_Cargo I got these results in National_Air_Cargo.png

Questions:

1. I am not clear as to why Average Load Factor per Route per Airline would be any different to Average Load Factor per Airline. As one can see in vast majority of cases the results for Average Load Factor per Route per Airline and Average Load Factor per Airline are the same, with one of the notable exceptions, namely Air India (see above);

2. When I select Air India, I get identical results for Average Load Factor per Route per Airline and Average Load Factor per Airline (see Air-India_selected.png). Why would selecting a row make Average Load Factor per Airline appear change from '-' to '74.3%' all of a sudden?

3. Selecting the first row of National Air Cargo yields the same results as selecting Air India, which means Average Load Factor per Airline shows up as the correct indicator of '29.0%'. However, selecting the second row, produces '-' in all columns (refer to selected_National_Air-Cargo.png). Why would this be the case?

thanks you

[Miles_Dyson]

Can anyone knowledgable to explain? Thanks