MS Excel - Example No. 6
1. Input data of egg weights measured before and after the change of light regime into a table (cells B3:B17 and C3:C17); calculation of mean value (average) of samples: in the cell B18 and C18 call menu Insert - Function - Statistical - AVERAGE; calculation of standard deviation (SD) for sample data: in cell B19 and C19 call menu Insert - Function - Statistical - STDEV (see examples 1, 2).
Calculation of paired t-test: in the cell B20 call menu Insert - Function - Statistical - TTEST:
2. Into field Array 1 in dialog window input cells for calculation - B3:B17 (measurements before the change of light regime), into field Array 2 input cells C3:C17 (measurements after the change of light regime), in Tails: 2, in Type: 1 (paired t-test); push the button OK to get result:
3. Displayed results of calculations:
6. Result of paired t-test: p=0.6578 indicates the probability of null hypothesis about equality of means (= probability of a error). As calculated p > 0.05, it means that difference between tested means is statistically insignificant.
Conclusion: As difference between mean value of egg weights before the change of light regime and after the change of light regime is statistically insignificant (p>0.05), the change of light regime didn´t influence the weights of eggs in layers.