If 83% of employers claim that Brand effects hiring great talent, than why do only 33% or 1/3 of those hiring managers measure that metric?

LinkedIn has now released Talent Brand Index. What is the Talent Brand Index?

According to LinkedIn  they measure billions of data transactions a year. Within this data they measure what individuals are doing, what they are looking at, which companies they are applying too and so on. 

What does Talent Brand Index Measure:

1. Reach: The number of people that are familiar with you as an employer. Measured by the number of people that view your company page or connect with them
2. Engagement: People that proactively engage your company by visiting your career page or company page.

My questions:

1. Is this data accurate if it is based only on the LinkedIn Network?
2. How skewed is the information if the vast majority of the companies able to afford these solutions are large corporate entities?

See the LinkedIn Commercial Here: