I am currently studying about different types of variable and their way to visualize them while studying about different variable I came to know that we can use frequency table to visualize any categorical variable and also we can convert any quantitative variable to ordinal variable to see his frequency table but I want to know why reverse process is possible means why we can not code ordinal variable to quantitive variable.
The answer is simple - because if you do so, the values which will come out of the analysis would not be of any use.
For example, let us say you are doing analysis on different sizes of bottle of coke. You have 300 mL bottle and 500 mL bottle.
Let us say you code these as quantitative variables and not as ordinal variables. Let us say you want to look at what is the size preference for a customer. In this case, if you use quant methods, you will come out with answers like average size of bottle purchased by an user is [a number between 300 - 500 mL] with standard deviation of [----another number----]
Now, if you think about it, these numbers are irrelevant for the problem you were trying to solve. The bottle can only come in one of the 2 sizes!
The problems of-course increase with more complex problems.
Hope this helps,