Which statement below is incorrect?

-the mean is not affected by the existence of an outlier.
-the median is not affected by the existence of an outlier.
-the standard deviation is affected by the existence of an outlier.
-the interquartile range is unaffected by the existence of an outlier.

-The mean is not affected by the existence of an outlier.

Step-by-step explanation:

An outlier is an ultimate value in a set of data that is very much higher or lower than the other numbers. Mean is the only central tendency which is affected by the outlier. (It also affect the standard deviation)

It can affect the mean of a data set by skewing the results so that the mean is no longer representative of the data set.

The median and the interquartile range is unaffected by the existence of an outlier.

your answer would be b

step-by-step explanation:

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.