**5.1. Definition**

NCI, which was the basis of PPCI, is the ratio of the number of paper-paper citations which the target paper got to the expected value of that of the same cohort papers in the world. NCI is calculated for paper by paper, so when it is applied to an aggregate, such as institutions or countries, the average per their publications' NCI is applied. On the other hand, PPCI is based on the rate of papers cited in patents in targets' publications. Indeed, it is preferable to apply the same definition as NCI to secure symmetry; we applied the abovementioned definition to avoid influence of limited highly cited papers, since the rate of papers cited from patents was

> ′ /*<sup>n</sup>* \_\_\_\_\_\_\_*ijd*) (*Nid*

′ : number of target *j*'s papers cited in patents with document type *d* published in discipline *i*;

: number of total papers cited in patents with document type *d* published in discipline *i*.

While the whole counting method was used to count Japanese sectors' publications in the previous study [9], the fractional counting method by number of addresses which appeared in each paper was used. The whole counting method always attributed one count to each target appeared in a paper, so they are easy to understand intuitionally; however, it often causes

Next, I tried to apply PPCI to three Japanese sectors (university, public institute, corporation) to show how PPCI could describe the scientific and technological impact of aggregate of meso (sector) level. This was mainly aimed to figure out on which level of aggregates PPCI could be

<sup>=</sup> <sup>∑</sup>*<sup>i</sup>* <sup>∑</sup>*d*(*Nid* <sup>×</sup> *nijd*

′ /*Nid* ′ )

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ <sup>∑</sup>*<sup>i</sup>* <sup>∑</sup>*<sup>d</sup> nijd*

*nijd*: number of target *j*'s papers with document type *d* published in discipline *i*;

*Nid*: number of total papers with document type *d* published in discipline *i*; and

∑*<sup>i</sup>* ∑*<sup>d</sup> nijd*

Hereafter, improved Normalized PPCI (Eq. (3)) is merely called as PPCI.

**4.2. Chronological changes of NCI and PPCI of Japanese sectors**

used. The chronological change of both NCI and PPCI was shown in **Figure 4**.

′ /*Nid*) (1)

(*Pj* <sup>+</sup> <sup>1</sup>) (3)

(2)

relatively smaller than that from papers. Improved PPCI was defined as Eq. (1):

where.

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*nijd*

*Nid* ′

*pijd* <sup>=</sup> (*nijd*

Target j's field weighted PPCI was calculated as follow:

To increase visibility, we normalized PPCI by Eq. (3):

Normalized *Pj* <sup>=</sup> (*Pj* <sup>−</sup> <sup>1</sup> \_\_\_\_\_)

*Pj* <sup>=</sup> <sup>∑</sup>*<sup>i</sup>* <sup>∑</sup>*<sup>d</sup> pijd* <sup>×</sup> *<sup>n</sup>* \_\_\_\_\_\_\_\_\_\_\_*ijd*

overrating to multiauthored papers.

I showed that tendencies of paper citations from high-feature-valued patents differed from whole patents in some cases. It is suggested that indicators based on high-featured-valued patents might reveal hidden structure of the targets' research performance.

I tried to develop another indicator symmetrical to the PPCI to use them in combination. Here, we introduced the indicators based on paper citations from high-feature-valued patents, named high-feature-valued patent-paper citation index (HFPPCI). HFPPCI is a generic name of set of indicators, since there were many kinds of patent feature values. Of the many kinds of patent feature values, I will show the analysis of three patent feature values (patent family size, patent-patent forward citations, and patent generality index) of Japanese sectors to examine the nature of HFPPCI as well as to show the tendencies of the Japanese sectors.

HFPPCI of target *j* in discipline *i* was defined as Eq. (4):

$$p\_{\;\,\psi}^{\;h} = \frac{\left(m\_{\;\psi}^{\;\;\;\phi}/n\_{\;\psi}\right)}{\{M\_{\;\;\;\phi}/N\_{\;\;\phi}\}}\tag{4}$$

where.

*nij* : number of target *j*'s papers published in discipline *i*;

*mij* ′ : number of target *j*'s papers cited in high-feature-valued patents published in discipline *i*;

*Ni* : number of total papers published in discipline *i*; and

*Mi* ′ : number of total papers cited in high-feature-valued patents published in discipline *i.*

To increase visibility, we normalize HFPPCI by Eq. (5):

$$\text{Normalized } P\_{\mathbb{H}}^{h} = \frac{\left(p\_{\vec{\imath}}^{h} - 1\right)}{\left(p\_{\vec{\imath}}^{h} + 1\right)}\tag{5}$$

**Figure 5.** PPCI and LPFPCI of Japanese university sector by discipline (1998–2000).

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**Figure 6.** PPCI and HFCPCI of Japanese university sector by discipline (1998–2000).

Here, the difference in document types was ignored, since the number of review papers cited from high-feature-valued patents was very few. Eq. (2) could be applied to aggregate *pij h* into the whole target level; however, the selection of disciplines was inevitable because paper citations from high-feature-valued patents occurred rarely and *Mi* ′ might be zero in some cases.

#### **5.2. Japanese sectors' PPCI and HFPPCI by discipline**

In this subsection, I tried to analyze the Japanese three sectors' technological impacts by discipline in Period 1 (1998–2000). HFPPCIs of three patent feature values were called as large patent family paper citation index (LPFPCI) for large patent family, high forward citation patent-paper citation index (HFCPCI) for the patents of high patent-patent forward citations, and high generality patent-paper citation index (HGPCI) for patents with a high patent generality index. Definition of high-feature-valued patents was same as Section 3.3: equal or more than 15 for patent family size, top 1% for patent-patent forward citations, and equal or more than 0.85 for patent generality index. In the following subsections, document types were ignored in the calculation of both PPCI and HFPPCI. Both PPCI (X-axis) and HFPPCI (Y-axis) were plotted in bubble charts, and the number of papers cited from high-feature-valued patents was presented as size of the circles in **Figures 5**–**13**.

#### *5.2.1. University*

For LPFPCI, each discipline in **Figure 5** was positioned in line to some extent. This roughly means that large patent families of most of the disciplines in the sector appeared in proportion to papers cited in patents. In this case, there were not very much special information that could be obtained from the LPFPCIs, because PPCI contained almost the same information as LPFPCI. However, it was suggested that the LPFPCI functioned robustly, since there were only few deviating cases.

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**Figure 5.** PPCI and LPFPCI of Japanese university sector by discipline (1998–2000).

family size, patent-patent forward citations, and patent generality index) of Japanese sectors to examine the nature of HFPPCI as well as to show the tendencies of the Japanese sectors.

> *<sup>h</sup>* <sup>=</sup> (*mij* ′ /*<sup>n</sup>* \_\_\_\_\_\_*ij*) (*Mi* ′ /*Ni*

: number of target *j*'s papers cited in high-feature-valued patents published in discipline *i*;

*<sup>h</sup>* <sup>=</sup> (*pij <sup>h</sup>* <sup>−</sup> <sup>1</sup> \_\_\_\_\_) (*pij*

′

: number of total papers cited in high-feature-valued patents published in discipline *i.*

Here, the difference in document types was ignored, since the number of review papers cited from high-feature-valued patents was very few. Eq. (2) could be applied to aggregate *pij*

the whole target level; however, the selection of disciplines was inevitable because paper cita-

In this subsection, I tried to analyze the Japanese three sectors' technological impacts by discipline in Period 1 (1998–2000). HFPPCIs of three patent feature values were called as large patent family paper citation index (LPFPCI) for large patent family, high forward citation patent-paper citation index (HFCPCI) for the patents of high patent-patent forward citations, and high generality patent-paper citation index (HGPCI) for patents with a high patent generality index. Definition of high-feature-valued patents was same as Section 3.3: equal or more than 15 for patent family size, top 1% for patent-patent forward citations, and equal or more than 0.85 for patent generality index. In the following subsections, document types were ignored in the calculation of both PPCI and HFPPCI. Both PPCI (X-axis) and HFPPCI (Y-axis) were plotted in bubble charts, and the number of papers cited from high-feature-valued patents

For LPFPCI, each discipline in **Figure 5** was positioned in line to some extent. This roughly means that large patent families of most of the disciplines in the sector appeared in proportion to papers cited in patents. In this case, there were not very much special information that could be obtained from the LPFPCIs, because PPCI contained almost the same information as LPFPCI. However, it was suggested that the LPFPCI functioned robustly, since there were only few deviating cases.

) (4)

*<sup>h</sup>* <sup>+</sup> <sup>1</sup>) (5)

might be zero in some cases.

*h* into

HFPPCI of target *j* in discipline *i* was defined as Eq. (4):

: number of target *j*'s papers published in discipline *i*;

: number of total papers published in discipline *i*; and

To increase visibility, we normalize HFPPCI by Eq. (5):

tions from high-feature-valued patents occurred rarely and *Mi*

**5.2. Japanese sectors' PPCI and HFPPCI by discipline**

was presented as size of the circles in **Figures 5**–**13**.

*5.2.1. University*

Normalized *Pij*

*pij*

where.

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*nij*

*mij* ′

*Ni*

*Mi* ′

**Figure 6.** PPCI and HFCPCI of Japanese university sector by discipline (1998–2000).

**Figure 9.** PPCI and HFCPCI of Japanese public sector by discipline (1998–2000).

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**Figure 10.** PPCI and HGPCI of Japanese public sector by discipline (1998–2000).

**Figure 7.** PPCI and HGPCI of Japanese university sector by discipline (1998–2000).

**Figure 8.** PPCI and LPFPCI of Japanese public sector by discipline (1998–2000).

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**Figure 9.** PPCI and HFCPCI of Japanese public sector by discipline (1998–2000).

**Figure 7.** PPCI and HGPCI of Japanese university sector by discipline (1998–2000).

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**Figure 8.** PPCI and LPFPCI of Japanese public sector by discipline (1998–2000).

**Figure 10.** PPCI and HGPCI of Japanese public sector by discipline (1998–2000).

**Figure 11.** PPCI and LPFPCI of Japanese corporation sector by discipline (1998–2000).

For HFCPCI, most disciplines seemed to distribute vertically, suggesting their relatively inconsistent natures in terms of HFCPCI within the sector (**Figure 6**). Two disciplines, immunology and plant and animal science, showed relatively high impact in both PPCI and HFCPCI.

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**Figure 13.** PPCI and HGPCI of Japanese corporation sector by discipline (1998–2000).

For HGPCI, the university sector seemed to consist of two clusters divided vertically, except for two small disciplines, plant and animal science and computer science (**Figure 7**). The upper cluster consisted of both physical and life sciences, while the lower consisted of life

There seemed to be almost no correlation between PPCI and LPFPCI shown in **Figure 8**, and it seemed interesting that relatively smaller circles were located above X-axis while larger circles were opposite. This arrangement was caused by the fact that the disciplines located above the X-axis tended not be cited from the large-sized patent families as a whole, so the Japanese public institute was positioned above average regardless of their small number of

Most of the disciplines, of which number of papers cited in patents ranked within the top 1% patent-patent forward citations were relatively large, were located on the fourth quadrant (**Figure 9**). Therefore, papers' impact on highly cited patents seemed to be below X-axis totally. This agrees with the coefficient of public institute's patent-patent forward citations,

sciences concerning biotechnology.

papers cited from large-sized patent families.

which was below zero as shown in **Table 4**.

*5.2.2. Public institute*

**Figure 12.** PPCI and HFCPCI of Japanese corporation sector by discipline (1998–2000).

**Figure 13.** PPCI and HGPCI of Japanese corporation sector by discipline (1998–2000).

For HFCPCI, most disciplines seemed to distribute vertically, suggesting their relatively inconsistent natures in terms of HFCPCI within the sector (**Figure 6**). Two disciplines, immunology and plant and animal science, showed relatively high impact in both PPCI and HFCPCI.

For HGPCI, the university sector seemed to consist of two clusters divided vertically, except for two small disciplines, plant and animal science and computer science (**Figure 7**). The upper cluster consisted of both physical and life sciences, while the lower consisted of life sciences concerning biotechnology.

#### *5.2.2. Public institute*

**Figure 11.** PPCI and LPFPCI of Japanese corporation sector by discipline (1998–2000).

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**Figure 12.** PPCI and HFCPCI of Japanese corporation sector by discipline (1998–2000).

There seemed to be almost no correlation between PPCI and LPFPCI shown in **Figure 8**, and it seemed interesting that relatively smaller circles were located above X-axis while larger circles were opposite. This arrangement was caused by the fact that the disciplines located above the X-axis tended not be cited from the large-sized patent families as a whole, so the Japanese public institute was positioned above average regardless of their small number of papers cited from large-sized patent families.

Most of the disciplines, of which number of papers cited in patents ranked within the top 1% patent-patent forward citations were relatively large, were located on the fourth quadrant (**Figure 9**). Therefore, papers' impact on highly cited patents seemed to be below X-axis totally. This agrees with the coefficient of public institute's patent-patent forward citations, which was below zero as shown in **Table 4**.

For HGPCI shown in **Figure 10**, two relatively large disciplines—Chemistry and Physics which were located above the X-axis, seemed to make a trend of public institute, because the coefficient of the sector in the column of high patent generality index in **Table 4** was positive.

and long-tailed nature of citations. If these indicators were used as monitoring tools, a long citation window would be a bottleneck for practical use. Exploring the possibilities of development of methods for shorter-time measurement and to show their availability and

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**4.** HFPPCI might be inevitably sensitive to small changes in time sequence. Paper citation from high-feature-valued patents is a rarer phenomenon than that from all patents—even the latter is rare. Therefore, only a few citations might yield large changes to values of indicators. Chronological changes of HFPPCIs should be traced to grasp to what extent they are sensitive, and also possibilities for relaxing the threshold to increase samples should be addressed.

In the study, I used the Connection Table between "Web of Science Core Collection" (WoSCC) and "NISTEP Dictionary of Names of Universities and Public Organizations," produced by

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[3] NISTEP. Japanese Science and Technology Indicators 2017. NISTEP Research Material No. 261. Tokyo: National Institute of Science and Technology Policy; 2017. DOI: 10.15108/

[4] Branstetter L, Ogura Y. Is academic science driving a surge in industrial innovation? Evidence from patent citations. NBER Working Paper No. 11561; Issued in August 2005

[5] Ahmadpoor M, Jones BF. The dual frontier: Patented inventions and scientific advance.

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limitations should be an important theme.

National Institute of Science and Technology Policy.

Address all correspondence to: yasuhiro.yamashita@jst.go.jp

Japan Science and Technology Agency, Tokyo, Japan

**Acknowledgements**

**Author details**

Yasuhiro Yamashita

**References**

rm261
