ToothGrowth Analysis

Ravi G. Ravichandran
3 January, 2017

Objective and Data

Objective: Analyze the effect of supplement and dosage on tooth growth

Dataset: ToothGrowth data in the R datasets package.

Structure of the Dataset:

str(ToothGrowth)

'data.frame':   60 obs. of  3 variables:
 $ len : num  4.2 11.5 7.3 5.8 6.4 10 11.2 11.2 5.2 7 ...
 $ supp: Factor w/ 2 levels "OJ","VC": 2 2 2 2 2 2 2 2 2 2 ...
 $ dose: Factor w/ 3 levels "0.5","1","2": 1 1 1 1 1 1 1 1 1 1 ...

Plot of Dataset

plot of chunk unnamed-chunk-3

Hypothesis Testing

Hypothesis: The mean difference between Vitamin C (VC) and Orange Juice (OJ) is not equal to 0

t.test(len ~ supp, data = ToothGrowth, conf.level = 0.90)$p.value

[1] 0.06063451

t.test(len ~ supp, data = ToothGrowth, conf.level = 0.95)$p.value

[1] 0.06063451

Conclusion

By examining the box plot and the results of the hypothesis testing, we can conclude the following:

For confidence interval 0.90: since p value is 0.06 (and lower than 0.10) hypothesis is TRUE.
For confidence interval 0.95: since p value is 0.06 (and more than 0.05) hypothesis is FALSE.
By looking at the box plot, we can conclude that OJ is more effective than VC for doses of 0.5 and 1.0.