A group of scientists were interested to see if drug A has any effect on the gro

Question

A group of scientists were interested to see if drug A has any effect on the growth of pathogenic S. aureus. They performed an experiment in triplicate with and without drug A. S. aureus was grown in two independent flasks containing 100 mL media overnight. In the morning, 1 mL of media containing S. aureus was added in independent flasks containing 100 mL media where one flask had drug A and the other had no drug. The growth profile was monitored by measuring the optical density at OD600. What test will you use? Explain why did you chose to use either paired or unpaired. With the obtained results, explain the results and possible errors in the experiment.

For my unpaired t-test (using a website) I got:

P value and statistical significance:
  The two-tailed P value equals 0.0705
  By conventional criteria, this difference is considered to be not quite statistically significant.

Confidence interval:
  The mean of OD without A minus OD with A equals 0.1000
  95% confidence interval of this difference: From -0.0133 to 0.2133

Intermediate values used in calculations:
  t = 2.4495
  df = 4
  standard error of difference = 0.041 Group OD without drug A OD with drug A Mean 0.6000 0.5000 SD 0.0500 0.0500 SEM 0.0289 0.0298 N 3 3

Explanation / Answer

For my unpaired t-test (using a website) I got:

P value and statistical significance:
  The two-tailed P value equals 0.0705
  By conventional criteria, this difference is considered to be not quite statistically significant.

i.e. They performed an experiment in triplicate with and without drug A are not significant (effect are quite same).

Confidence interval:
  The mean of OD without A minus OD with A equals 0.1000
  95% confidence interval of this difference: From -0.0133 to 0.2133

Intermediate values used in calculations:
  t = 2.4495
  df = 4
  standard error of difference = 0.041

The results of the unpaired procedure are quite different, however. An unpaired t-test results in a t-value of 2.4495, and a p-value of 0.0705. Based on such results, we would fail to reject the null hypothesis and would conclude that there is no difference in the performance of the with and without drug A.

Group OD without drug A OD with drug A Mean 0.6000 0.5000 SD 0.0500 0.0500 SEM 0.0289 0.0298 N 3 3

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