Absolute Scaling vs Perceptual Scaling of Map of India
Absolute Scaling
Absolute Scaling – Cities with Population Greater than 2 Million in India
Advantages of Absolute Scaling
- The advantages to this method are that circles are scaled accurately, and the user is able to measure the symbol to acquire an accurate data response.
- Fewer problems and confusion can arise when symbols are measured directly to the value.
Disadvantages of Absolute Scaling
- With human perception we tend to underestimate areas, and this can lead users to have inaccurate perception on values of the symbols by seeing the larger symbols smaller than they truly are.
Perceptual Scaling
Perceptual Scaling – Cities with Population Greater than 2 Million in India
Advantages of Perceptual Scaling
- The strength of perceptual scaling is that symbols are perceived more accurately.
Disadvantages of Perceptual Scaling
- If a user were to measure the symbols, they would gage the wrong value.
- The scaling is based on the average person and ignores a broad range of users that vary from the average.
Proportional Symbol Map
This week I learned there are 3 types of proportional symbol maps:
- Absolute (or mathematical) Scaling: Size of the symbol is in direct proportion to the data value. Formula: ri = (vi/vL)0.5*rL
- Perceptual Scaling: Size of the symbol is slightly larger than the actual value. This is to compensate for the underestimation of the human eye that tends to estimate the value as less than its true value by the size of the symbol. Formula: ri = (vi/vL)0.57*rL
- Range Graded: The data is classified into classes represented by a size for a range of data values. Classification methods include Equal Interval, Quantiles, Standard Deviation, or Natural Breaks.
What I learned:
- Improved on my skills in Excel using formulas/equations.
Improvements for the future (takeaways):
- I would start the size of the proportional circles larger than what I did in this lab. It was quite time consuming to change each circle size.