# How to interpret axis of Histogram and distribution curve?

After doing statistical analysis of data I got the below figures: The data contains a line length in meters which is represented with Line(m). The purpose here is to confirm the distribution behavior of line lengths(m). Now, based on above two figures:

1. What kind of information x-axis and y-axis of both figures convey? Particularly for the distribution curve (pdf)?. From the first figure, it is somehow clear that it shows the percentage of the data fall within that region.
2. The x-axis of second figure shows the values from [0 - 80]. Does this means line length (m)?

## 1 Answer

1. First figure shows Frequency(Y-axis) distribution over varied values of Line data(X-axis). Similar information gets conveyed by your second figure as well, but second one provides a deeper insight to frequency fluctuation over smaller bins of Line data. Additionally in second figure, various types (Lognorm, Exponential, etc.) of distribution gets line traced on the population distribution. This additional line helps to figure out co-ordinates on this grid where there is a spike or dip in Frequency values based on Line data.

2. Every distribution has a spread or else mathematical computations won't be feasible for any kind of inference/analysis. For Line data, in both your plots, X-axis takes that responsibility. Unit (m specified by you) associated to values shall entirely depend on nature of your Line data feature.

Also, I remember writing a series of articles and creating a GitHub repository few years back on Statistical data visualization with Python and Seaborn which might be of some help. So please feel free to check, if required.

• @Random...Thank you for a great answer. What are the units at x-axis and y-axis? Are the axis are unitless as per here math.stackexchange.com/questions/1000271/… – Case Msee Jan 31 '20 at 1:51
• Additionally, the x-axis of the second figure shows the data values(line length)? or probabilities calculated by pdf. – Case Msee Jan 31 '20 at 1:52
• Units of represented values on X as well as Y axis solely depend upon the feature(column), which is being plotted on respective axis. Thus the axes inherit same values. Now if we have applied some function on top of this column, then respective axes will represent values with units based on outcome of that applied function. So currently, unless you've explicitly applied any function to compute probability, X-axis continues to hold feature values from 'Line length' with same values as in data. – Random Nerd Jan 31 '20 at 8:20