The complete guide to understanding mean deviation and standard deviation.
Standard deviation is a commonly used term in Statistics. It has applications in Mathematics and Economics as well. This blog gives you a basic idea of Mean Deviation and Standard Deviation and how to calculate these.
I am a math educator having taught Mathematics for three decades both at the high school and college level. So here's showing you how incredibly easy and scoring this topic is. My students ace this topic because it is so incredibly easy and question on this topic are pretty direct.
So, let's start the magical journey of learning!
Keep in mind that mean deviation and standard deviation are two ways of measuring the dispersion of data. Mean Deviation basically gives you how far the data is distributed from the mean or median. So, in Mean Deviation problems, you need to calculate two types, mean deviation about the mean and mean deviation about the median.
Again, there are two types of problems. Firstly, we have a set of discrete observations . These are easier to calculate.
Then we have a frequency distribution which may be grouped or ungrouped. For problems of these type, you will use the formula and evaluate. Formulas are given in the images.
This topic is fairly easy and my students usually get it right provided they remember the correct formula. Mean deviation is not a very reliable method of measuring the deviation. Hence we have the standard deviation which is a more reliable and widely used method to evaluate the dispersion.
The mean of the squared deviations is called the variance and standard deviation is the square root of the variance. You calculate the standard deviation for a set of discrete values and for a frequency distribution. The formula for calculating the standard deviation for a set of discrete values is quite simple.
For calculating the standard deviation for a frequency distribution with equal class intervals, you can use three methods. First, you have the direct method. If the values are large, you have two methods to calculate the standard deviation, namely, the Shortcut method or the Deviation method and the Step Deviation method.
Note that these two methods are more or less similar, with a slight difference. As I tell my students, you are free to use any formula of your choice in the exams. But keep in mind, that if a particular question demands the use of a particular method, then you have to abide by the question.
How Online Tutoring helps!
I have given you a brief gist on how you should go about preparing Mean Deviation and Standard Deviation. If you still need some help or guidance, you can contact me for online tutoring. You would require around three sessions of an hour each to understand this topic.
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