feat(notes): Add explanation of shares and ratios

03-documentation/measures.md

@@ -32,6 +32,15 @@ GGini; GTheil; GCOV
 
 ### Relative
 
+1. **Share:**
+   - A share typically refers to a unit of ownership in a company, representing a proportional claim on its assets and earnings. Shares are also known as
+ stocks or equity.
+2. **Ratio:**
+   - A ratio, on the other hand, is a comparison of two quantities. It expresses the relationship between two numbers and is often used to analyze
+ financial and economic data.
+    For example a study analyzing rural-urban income inequality using "the percentage deviation of real wages," it sounds like it might involve a ratio. The term "percentage deviation" implies a measure of how much a variable deviates from its expected or average value, expressed as a percentage. In this case, the ratio could be the percentage deviation of real wages between rural and urban areas, helping to assess the income inequality between the two.
+
+    The income ratio can be calculated as the ratio of the real wages of urban workers to rural workers. If the real wages for rural workers are decreasing ( deviating into the negative), it means the income of rural workers is declining relative to urban workers. This would likely result in an increase in the income ratio because the numerator (urban workers' wages) is relatively higher than the denominator (rual workers' wages). In summary, if the policy leads to a negative percentage deviation of real wages for rural workers, it would likely increase the income ratio between urban and rural workers.
 
 * ratios of quantiles to each other (division of various quantiles)
 
@@ -61,3 +70,4 @@ GGini; GTheil; GCOV
 
 * Foster-Greer-Thorbecke-class distribution (@Sotomayor2021)
 
+