Interim standings after FIVE snow storm forecasting Contests … as of 04-MAR-19.
Under the ‘two-thirds’ rule … forecasters who have entered at least FOUR forecasts are included in this interim summary.

To qualify for ranking in the Interim and final ‘End-of-Season’ standings … a forecaster must enter at least two-thirds of all Contests.

If a forecaster issued more than enough forecasts to qualify for ranking … only the lowest SUMSQ Z-scores necessary to qualify are used in the computing the average SUMSQ Z-score.

IOW … if you made nine forecasts … only your six best SUMSQ Z-scores are used to evaluate your season-to-date / end-of-season performance.

You can think of it as dropping the worst test score before your final grade is determined.


The reasons we have this rule:

1)  makes it possible to miss issuing a forecast or two throughout the season and still be eligible for Interim and ‘End-of Season’ ranking and

2)  encourage forecasters to take on difficult and/or late-season storms without fear about how a bad forecast might degrade their overall 'season-to-date' performance score(s).



The average ‘SUMSQ Z-score’:  the Contest/s primary measure of forecaster performance.

This metric measures how well the forecaster/s expected snowfall 'distribution and magnitude' for _all_ forecast stations captured the 'distribution and magnitude' of _all_ observed snowfall amounts.

A forecaster with a lower average SUMSQ Z-score has made more skillful forecasts than a forecaster with higher average SUMSQ Z score.



The 'Storm Total Precipitation error’ statistic:  the absolute arithmetic difference between a forecaster/s sum-total snowfall for all stations and the observed sum-total snowfall.

This metric … by itself …is not a meaningful measure of skill …but can provide additional insight of forecaster bias.



The 'Total Absolute error' statistic:  the sum of absolute errors regardless of whether you over-forecast or under-forecast.

This metric measures the magnitude of a forecast’s errors.



The 'Average Absolute Error':  ‘Total Absolute Error’ divided by the number of stations where snow was forecast or observed.



The ‘RSQ error’ statistic:  a measure of the how well the forecast snowfall captured the variability of the observed snowfall.

Combined with the SUMSQ error statistic … RSQ provides added information about how strong the forecaster/s ‘model’ performed.