The expected on-time share is an estimate from days with similar weather in our own history.

The weather we use

• Daily figures for Ottawa Macdonald-Cartier airport from Environment and Climate Change Canada: highest temperature, rain, snow and wind.
• Each day gets a type: dry, wet, snowy or heavy, by freezing, cool or warm. Heavy means a lot of precipitation or snow.

How the expected value is worked out

• For each day of the month we take the average on-time share of days of the same type outside that month.
• The month’s expected value is the average of those. The range is an interval, built from the spread of days and the uncertainty of each average.
• The observed value is the average of the same days, so the two are compared on identical days. It is "better" or "worse" only when outside the range.

When we say nothing

• A type needs enough days of history, and most of the month’s days must have one. Otherwise the page says "not estimated yet".
• Only days when both operators were fully captured count. Warnings and storms that ECCC issues are not in the daily record, so they are not used.

Saan nanggagaling ang mga numero

• Environment and Climate Change Canada, daily climate data (Open Government Licence - Canada)
• Our observed on-time share, day by day

Bersyon ng pamamaraan at talaan ng mga pagbabago

Ang inilathalang buwan ay hindi na nagbabago. Kung babaguhin ang pamamaraan, ang mga nakaraang buwan ay mananatili sa pamamaraang ginamit sa pagkuwenta nito.

• Bersyon 1 · Oktubre 28, 2026. First published. The on-time share we would expect for the month’s weather, from our own history, with a range.