Castaldi, C., Frenken, K., & Los, B. (2015). Related Variety, Unrelated Variety and Technological Breakthroughs: An Analysis of US State-level Patenting. Regional Studies, 49(5), 767-781. http://dx.doi.org/10.1080/00343404.2014.940305
The original paper included some incorrect statements and table entries due to a mix up of US state labels in the data analysis. The key claims from the study remain unchanged. Tables 2, 3 and 4 are updated and a few state labels in the text are now corrected.
Results section:
p. 773
Paragraph 2:
The sentence: ‘In 1977, the top-five patent producers in that year (California, New York, New Hampshire, Indiana and Pennsylvania) produced as much as 45% of all patents considered.’ should read: ‘In 1977, the top-five patent producers in that year (California, New York, New Jersey, Illinois and Pennsylvania) produced as much as 45% of all patents considered.’
The sentence ‘In 1999 the share of the top five was also 45%, but the composition of the top five changed slightly (California, Texas, New York, Michigan and New Hampshire).’ should read: ‘In 1999 the share of the top five was also 45%, but the composition of the top five changed slightly (California, Texas, New York, Michigan and New Jersey).’
Paragraph 3:
The sentence ‘Alaska, South Dakota, Wyoming and Nevada generated less than one superstar patent per year over the period 1977-99.’ should read: ‘Alaska, South Dakota, Wyoming and North Dakota generated less than one superstar patent per year over the period 1977-99.’
The sentence: ‘Idaho and Minnesota averaged shares of 7.1% and 6.9%, while there are shares of 6.7%, 6.7% and 6.4% for California, New Mexico and Massachusetts, respectively.’ should read: ‘Idaho and Minnesota averaged shares of 7.1% and 6.9%, while there are shares of 6.7%, 6.7% and 6.4% for California, Nevada and Massachusetts, respectively.’
The sentence: ‘At the bottom end are mainly found states that produced only a few patents in general such as South Dakota (1.9%), Nevada (2.1%) and Arkansas (2.6%).’ should read: ‘At the bottom end are mainly found states that produced only a few patents in general such as South Dakota (1.9%), North Dakota (2.1%) and Arkansas (2.6%).’
Paragraph 4:
The sentence: ‘Alaska, Nevada and Wyoming are examples of states that did not generate many patents, and it could be expected that their patents could not cover the entire technological range to a substantial extent.’ should read: ‘Alaska, North Dakota and Wyoming are examples of states that did not generate many patents, and it could be expected that their patents could not cover the entire technological range to a substantial extent.’
Paragraph 5:
The sentence: ‘New Hampshire is the prime example of a heavy producer of patents with little semi-related variety.’ should read: ‘New Jersey is the prime example of a heavy producer of patents with little semi-related variety.’
The sentence: ‘Turning to RV, a different top three is found: Indiana (1.83), Ohio (1.79) and Michigan (1.75).’ should read: ‘Turning to RV, a different top three is found: Illinois (1.83), Ohio (1.79) and Michigan (1.75).’
p.774
Paragraph 1:
The sentence ‘Idaho (0.90), Rhode Island (0.98) and New Jersey (1.00) are examples of states that produce sizable numbers of patents, but with little related variety.’ should read: ‘Idaho (0.90), Rhode Island (0.98) and New Mexico (1.00) are examples of states that produce sizable numbers of patents, but with little related variety.’
p. 775
Paragraph 2:
The sentence ‘Semi-related variety is also found to be ‘detrimental’ for breakthroughs.’ should read: ‘Semi-related variety is also found to be somewhat ‘detrimental’ for breakthroughs, but this effect is only significant at a 10% confidence level.’
p. 776
Paragraph 1:
Before the sentence ‘All in all, the additional estimations are reassuring that spatial dependence effects are not relevant at the state level.’ an additional sentence should be added: ‘In the models predicting the share of superstars, RDneighbours is statistically significant and the coefficient estimates confirm the claim over the role of unrelated variety.’
p. 779
Note 7: ‘New Mexico’ should read: ‘Nevada’