Explain why a graphical display might be skewed. How do you ensure data isn't skewed?
A graphical display representing data might be skewed by data points that change its direction. These points need to be eliminated to prevent the skew.
Data points that are far away from the normal data (above or below the normalized graph) are called outliers. These are points that are not in line with the rest of the data collected, and may be the result of errors in collection or reporting.
Because of the negative effect of outliers on the representation of the data, there are advocates of using the median rather than the mean for graphical display. This would be one method of removing the effect of outliers on skewing the data.
Another method of ensuring data is not skewed is to eliminate the outlier. An obvious outlier can be simply dropped out of the data and by its removal, it will not affect the representation as much as it would if it was present.
The preferred method is to re-evaluate the data, checking for errors, or repeating the data collection. This will often result in a clearer indication of the correct data points and their representation.