The categorical statistical metrics such as Probability of Detection (POD), False Alarm Ratio (FAR), and Critical Success Index (CSI) have been used for the detection of precipitation capability of satellite precipitation products with reference precipitation products depending on rainy and non-rainy days. POD represents the hit rate, which means the ratio of correctly detected by satellite as a rainfall event to the actual total rainfall events measured by reference data. It varies from 0 to 1 (1 is the ideal value). FAR is known as a false rate. It represents the ratio of satellite-detected falsely as a rainfall event to the total rainfall events detected by satellite. It varies from 0 to 1 (0 is the perfect value). CSI is the ratio of correctly detected rainfall events by satellite to the total number of hits, misses, and false alarms. CSI values range from 0 to 1 (1 is a suitable value), as shown in Table 3.
Details of the continuous and categorical statistical metrics used for evaluating the precipitation products
| Statistic Metric | Equation | Perfect Value | Description |
|---|---|---|---|
| Nash-Sutcliffe Coefficient Efficiency (NSE) |  | 1 | It measures the model performance |
| Correlation Coefficient (CC) |  | 1 | It represents the degree of agreement in between observed and measured data |
| Root Mean Square Error (RMSE) |  | 0 | It represents the magnitude of average error |
| Percent Bias (Pbias) |  | 0 | It represents the deviation between observed and measured data |
| Mean Absolute Error (MAE) |  | 0 | It measures the average difference in between observed and estimated data |
| Probability of Detection (POD) | POD = H/(H + M) | 1 | It represents the detected rainfall events correctly by satellite out of rainfall events by reference data. |
| False Alarm Ratio (FAR) | FAR = F/(F + H) | 0 | It represents the false, detected rainfall event by satellite when reference data showed no rainfall |
| Critical Success Index (CSI) | CSI = H/(H + M + F) | 1 | It shows more accuracy when correct negative values are not considered |
| Statistic Metric | Equation | Perfect Value | Description |
|---|---|---|---|
| Nash-Sutcliffe Coefficient Efficiency (NSE) | | 1 | It measures the model performance |
| Correlation Coefficient (CC) | | 1 | It represents the degree of agreement in between observed and measured data |
| Root Mean Square Error (RMSE) | | 0 | It represents the magnitude of average error |
| Percent Bias (Pbias) | | 0 | It represents the deviation between observed and measured data |
| Mean Absolute Error (MAE) | | 0 | It measures the average difference in between observed and estimated data |
| Probability of Detection (POD) | POD = H/(H + M) | 1 | It represents the detected rainfall events correctly by satellite out of rainfall events by reference data. |
| False Alarm Ratio (FAR) | FAR = F/(F + H) | 0 | It represents the false, detected rainfall event by satellite when reference data showed no rainfall |
| Critical Success Index (CSI) | CSI = H/(H + M + F) | 1 | It shows more accuracy when correct negative values are not considered |