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<br />Table 1. Three t-tests comparing peak discharge from different time periods. There is a <br />significant difference between the 2 sample means if the absolute value of the t-statistic is greater <br />than the t-critical value. These tests show that the peak floods from the early part of the century <br />are statistically different from the two later time periods. Peak floods for the decades directly <br />before (1965-1983) and after Taylor Draw Dam (1984-1997) are not significantly different. <br /> <br />Time periods <br /> <br />1923- 1965- <br />1965 1983 <br /> <br />1923- 1984- <br />1965 1996 <br /> <br />1965- 1984- <br />1983 1996 <br /> <br />Mean Peak Discharge (m3/s) 123 98 123 97 98 97 <br />Variance 1789 793 1769 1501 737 1501 <br />Observations 59 27 59 17 27 17 <br />Pooled Variance 1448 1711 1026 <br />Hypothesized Mean Difference 0 0 0 <br />df 84 74 42 <br />t Stat 2.83 2.30 0.12 <br />P(T<==) two-tail 0.006 0.024 0.903 <br />t Critical two tail 1.99 1.99 2.02 .. <br />Difference between periods significant diff significant diff significant diff <br /> <br />33 <br />