Trend analysis was performed using the MK test of the null hypothesis of trend absence in the SPI time series, against the alternative of trend. The result of the test is returned in hm = 0, for all SPI series, and indicates a failure to reject the null hypothesis at the 90% significance level. Moreover, Table 3 indicates a failure to reject the null hypothesis at the 90% significance level since for SPI3, SPI6, SPI9, SPI12 and SPI24, which means that all investigated trends are statistically insignificant.
Table 3
Results of MK test (Bahir Dar station 1960–2008)
| SPI time series | SPI 3 | SPI 6 | SPI 9 | SPI 12 | SPI 24 |
|---|---|---|---|---|---|
| hm | 0 | 0 | 0 | 0 | 0 |
| P value | 0.5954 | 0.9505 | 0.7478 | 0.9246 | 0.1164 |
| ZMK | 0.173 | 0.402 | 1.127 | 0.896 | 0.249 |
| Type of trend | Insignificant | Insignificant | Insignificant | Insignificant | Insignificant |
| SPI time series | SPI 3 | SPI 6 | SPI 9 | SPI 12 | SPI 24 |
|---|---|---|---|---|---|
| hm | 0 | 0 | 0 | 0 | 0 |
| P value | 0.5954 | 0.9505 | 0.7478 | 0.9246 | 0.1164 |
| ZMK | 0.173 | 0.402 | 1.127 | 0.896 | 0.249 |
| Type of trend | Insignificant | Insignificant | Insignificant | Insignificant | Insignificant |