added references for CRPS for ensembles

docs/paper.bib

@@ -229,4 +229,32 @@ @article{griffiths2021circular
   year={2021},
   publisher={CSIRO Publishing},
   doi={10.1071/es21010}
-}
+}
+ @article{Ferro_2013, 
+	title={Fair scores for ensemble forecasts: Fair Scores for Ensemble Forecasts}, 
+	volume={140}, 
+	ISSN={0035-9009}, 
+	url={http://dx.doi.org/10.1002/qj.2270}, 
+	DOI={10.1002/qj.2270}, 
+	number={683}, 
+	journal={Quarterly Journal of the Royal Meteorological Society}, 
+	publisher={Wiley}, 
+	author={Ferro, C. A. T.}, 
+	year={2013}, 
+	month=dec, 
+	pages={1917–1923}
+  }
+ @article{Gneiting_2007, 
+	title={Strictly Proper Scoring Rules, Prediction, and Estimation}, 
+	volume={102}, ISSN={1537-274X}, 
+	url={http://dx.doi.org/10.1198/016214506000001437}, 
+	DOI={10.1198/016214506000001437}, 
+	number={477}, 
+	journal={Journal of the American Statistical Association}, 
+	publisher={Informa UK Limited}, 
+	author={Gneiting, Tilmann and Raftery, Adrian E}, 
+	year={2007}, 
+	month=mar, 
+	pages={359–378}
+ }
+

docs/paper.md

@@ -54,7 +54,7 @@ In order to meet the needs of researchers, `scores`:
 
 ## Roadmap and Future Development
 
-At the time of writing, the scores contained in this package are: Mean Squared Error (MSE), Mean Absolute Error (MAE), Root Mean Squared Error (RMSE), the Fixed Risk Multicategorical (FIRM) score [@Taggart:2022a], Continuous Ranked Probability Score (CRPS) for Cumulative Distribution Functions (CDFs) (including threshold-weighting, see [@Gneiting:2011]), CRPS for ensembles, the Flip-Flop Index [@Griffiths:2019; @griffiths2021circular], Receiver Operating Characteristic (ROC) curves, the quantile score, and the Murphy score [@Ehm:2016]. It also includes the Diebold-Mariano statistical test [@Diebold:1995] with both the [@Harvey:1997] and [@Hering:2011] modifications. Additionally it contains isotonic regression which is becoming an increasingly important tool in forecast verification and can be used to generate stable reliability diagrams [@dimitriadis2021stable]. We anticipate more scores, metrics and statistical techniques will be added over time.
+At the time of writing, the scores contained in this package are: Mean Squared Error (MSE), Mean Absolute Error (MAE), Root Mean Squared Error (RMSE), the Fixed Risk Multicategorical (FIRM) score [@Taggart:2022a], Continuous Ranked Probability Score (CRPS) for Cumulative Distribution Functions (CDFs) (including threshold-weighting, see [@Gneiting:2011]), CRPS for ensembles [@Gneiting_2007], [@Ferro_2013], the Flip-Flop Index [@Griffiths:2019; @griffiths2021circular], Receiver Operating Characteristic (ROC) curves, the quantile score, and the Murphy score [@Ehm:2016]. It also includes the Diebold-Mariano statistical test [@Diebold:1995] with both the [@Harvey:1997] and [@Hering:2011] modifications. Additionally it contains isotonic regression which is becoming an increasingly important tool in forecast verification and can be used to generate stable reliability diagrams [@dimitriadis2021stable]. We anticipate more scores, metrics and statistical techniques will be added over time.
 
 The `scores` roadmap includes: