What does the Herfindahl-Hirschman Index measure?

What does the Herfindahl-Hirschman Index measure?

The term “HHI” means the Herfindahl–Hirschman Index, a commonly accepted measure of market concentration. The HHI is calculated by squaring the market share of each firm competing in the market and then summing the resulting numbers. The HHI takes into account the relative size distribution of the firms in a market.

What is the difference between HHI and concentration ratio?

The Herfindahl-Hirschman Index (HHI) provides a more complete picture of industry concentration than the concentration ratio does. The HHI avoids the problem that concentration ratios do not reflect changes in the size of the largest firms.

In what ways do concentration ratios and Herfindahl indexes differ?

Concentration ratio of market concentration is usually measured as the sum of the market shares of four, eight or twelve largest companies in an industry. Herfindahl-Hirschman index of market concentration is expressed as the sum of squared market shares of all firms in an industry.

What is the highest possible Herfindahl-Hirschman Index HHI score?

The Herfindahl-Hirschman Index (HHI) takes into account the relative size distribution of the companies that compete in a market. The larger the number of firms of relatively equal size the nearer to zero it approaches, and reaches its 10,000 maximum points when a market is controlled by just one firm.

How do I calculate the Herfindahl Index?

You can calculate Herfindahl Index by squaring the market share for each firm (up to 50 firms) and then adding the squares. In a perfectly competitive market, HHI should approach zero.

How do you interpret concentration ratios?

The concentration ratio ranges from 0% to 100%, and an industry’s concentration ratio indicates the degree of competition in the industry. A concentration ratio that ranges from 0% to 50% may indicate that the industry is perfectly competitive and is considered a low concentration.

Why is the largest possible value of the Herfindahl index is 10000?

The largest possible value of the Herfindahl index is 10,000 because: An industry with an index higher than 10,000 is automatically regulated by the Justice Department An index of 10,000 corresponds to 100 firms with a 1% market share each An index of 10,000 corresponds to a monopoly firm with 100% market share.

What is the four firm concentration ratio formula?

The four-firm concentration ratio is calculated by adding the market shares of the four largest firms: in this case, 16 + 10 + 8 + 6 = 40. This concentration ratio would not be considered especially high, because the largest four firms have less than half the market.

Which is an example of the Herfindahl-Hirschman Index?

The measure is essentially equivalent to the Simpson diversity index, which is a diversity index used in ecology; the inverse participation ratio (IPR) in physics; and the effective number of parties index in politics. For instance, we consider two cases in which the six largest firms produce 90% of the goods in a market.

What’s the difference between Herfindahl index and normalized Index?

There is also a normalized Herfindahl index. Whereas the Herfindahl index ranges from 1/ N to one, the normalized Herfindahl index ranges from 0 to 1. It is computed as: where again, N is the number of firms in the market, and H is the usual Herfindahl Index, as above.

Can a industry have a lower Herfindahl than a 3 firm industry?

An industry with 3 firms cannot have a lower Herfindahl than an industry with 20 firms when firms have equal market shares. But as market shares of the 20-firm industry diverge from equality the Herfindahl can exceed that of the equal-market-share 3-firm industry (e.g., if one firm has 81% of the market and the remaining 19 have 1% each H=0.658).

When to use exponential entropy in a distribution?

Exponential entropy measures the extent of a distribution, and can be used to avoid the case of singularity when the weighted average entropy of some variables is zero, H ¯ ( X) = 0. Campbell, L. “Exponential Entropy as a Measure of Extent of a Distribution.”.