Table 2 Welch’s two-sample t test analysis
Site 1 Site 2 Site 3 Site 4
Sample A Sample B Sample A Sample B Sample A Sample B Sample A Sample B
Mean 241.65 134.25 159.12 65.77 144.86 57.45 75.78 63.20
Observations 36 35 36 35 36 35 36 35
Hypothesized mean difference 0 0 0 0
Degree of freedom 62 38 40 42
95% confidence interval (71.05, 143.75) (69.45, 116.99) (63.14, 111.65) (1.09, 24.05)
t-statistic 5.91 7.94 7.28 2.20
P (T ≤t) one-tail 0.00000015 0.0000000014 0.0000000074 0.03
t Critical one-tail 1.67 1.68 1.68 1.68