Analysis of Trend and Periodicity in Long-Term Annual Rainfall Time Series of Nigeria - Hydrologic Time Series Analysis: Theory and Practice - page 259

Table 12.3. Results of parametric and nonparametric trend tests for annual rainfalls of three zones and entire Nigeria

Data Time Least square regression test Mann-Kendall test

type series

Mean slope Test- Significance Median slope Test- Significance

(mm/year) statistic (mm/year) statistic

Guinea -0.90 -1.65 + -1.07 -1.88 +

Savannah -0.75 -1.85 + -0.85 -1.94 +

Including outlier

Sahel -0.63 -1.60 ns -0.63 -1.51 ns

Nigeria -0.76 -2.02 * -0.83 -2.16 *

Guinea -0.71 -1.37 ns -0.98 -1.71 +

Savannah -0.63 -1.59 ns -0.80 -1.77 +

Excluding outlier

Sahel -0.55 -1.40 ns -0.57 -1.35 ns

Nigeria -0.63 -1.75 + -0.74 -2.00 *

s

Note: +Trend is significant at 1% significance level; * Trend is significant at 5% significance level; ns: Trend is not significant.