In: Statistics and Probability
The following data (Dobson, 1983) from an experiment providing the dried weight of plants obtained under the condition of a certain treatment is given by 4.65, 4.35, 4.40, 3.59, 5.87, 3.89, 6.02, 4.92, 4.30, 4.23. (A) Find the sample mean, standard deviation (SD) and standard error (SE) of the data. (B) What will happen to SD and SE if you increase the sample size? (C) Determine a 90% confidence interval for the mean dried weight of all plants under this particular condition of a certain treatment. (D) Repeat part (C) using R.
(a) Sample mean = = 4.622
Variance = = 0.62032889
Standard Deviation = sqrt ( Variance ) = 0.7876096
(b) If the sample size is increased, then the variability in the
sample is
decreased which leads to a decrease in the value of standard
deviation and thus,
in the value of standard deviation.