The data distribution can be tested using descriptive statistics and visuals such as histograms, box plots, and normal quantile plots. The figure above shows the descriptive statistics, boxplot histogram, and quantile graph of KC-135 costs in various locations. A normally distributed data has equal mean, mode, and median. The mean for KC-135 flight 4.43 is greater than the median, 2.9, implying that the data is skewed to the right. The histogram and box plot confirm the positive skewed as they show a tail to the right, meaning that there are cases of abnormally high costs in some locations. The normal quantile plot is a plot of z-score against costs. The z-scores estimate the number of standard deviations that a data point is below or above the mean. A data point is considered as an outlier when the z-score is above or below 3. Although the quantile graph shows that all the data points are within three standard deviations above or below the mean, several data plots are located far above the mean, suggesting positive skewness. Most data plots also lie outside the line of best fit hence confirming that the KC-135 data is not normally distributed.
The z-score for F-35 costs lies within the range of -3 to 3 standard deviations meaning that there are no outlier costs. Outliers refer to data points that are unreasonably above or below the mean. A probability of less than the assumed level of significance, 0.05, also shows that a data point has significantly low chances of occurring with a normal distribution. All probabilities are above 0.05, implying that all the data points occur within the normal distribution range. The mean F-35 cost, 6.02, is significantly higher than the median, 2.8, suggesting that the data is skewed to the right. The positive skewed is confirmed by the tail to the right, as shown in the histogram and boxplot. Nearly all the data points on the normal quantile plot fall outside the line of best fit, indicating that the data is skewed.
Delegate your assignment to our experts and they will do the rest.
In conclusion, the costs of the squadrons in different locations are skewed. Although the expenses lie within the normal distribution range of between -3 and 3 standard deviations from the mean, histogram, boxplots, and normal quantile graph indicate that the cost data is skewed.
