Foot drop Common Causes. Introduction: This information shows the various causes of Foot drop, and how common these diseases or conditions are in the general population. This is not a direct indication as to how commonly these diseases are the actual cause of Foot drop, but gives a relative idea as to how frequent these diseases are seen overall.
Variability refers to how spread out a group of data is. The common measures of variability are the range, IQR, variance, and standard deviation. Measures of variability are descriptive statistics, which means they can only be used to describe the study data.
Variance and covariance are two measures used in statistics. Variance is a measure of the scatter of the data, and covariance indicates the degree of change of two random variables together. Variance is rather an intuitive concept, but covariance is defined mathematically in not that intuitive at first.