Introduction to Statistics - Essay Example

a) Proportion of affected patients was with the 95% confidence interval for the proportion of stroke patients who become clinically depressed given by . The confidence interval indicates with a confidence coefficient of 0.95 that the true proportion of stroke patients who become clinically depressed lies within this interval. b) To evaluate the claim of the health magazine, we check whether the confidence interval contains 60% of stroke sufferers. Since 0.60 is within the confidence interval, we conclude that the claim by the health magazine is consistent with the observed data (Mendenhall en Sinchich). c) The assumptions for the confidence interval to be valid include large sample size to ensure the validity of the normal approximation.

The sample size of 79 is large enough to guarantee the validity of the normal approximation. d) Sample size to be used to achieve a 99% level of confidence that the sample proportion of stroke patients suffering from depression is within 0.025 of the true proportion is computed from the following formula. b) The main assumption for the validity of the confidence interval computed is that the sample should be drawn from a normal distribution or asymptotically, it should tend to a normal distribution.

This assumption is violated since from the boxplot, the distribution of the temperature is right skewed. This is evident from the unequal length of whiskers of the boxplot, with a longer whisker for data to the right of the