受験番号/Examinee’s Number

令和 4 年度 2022 Academic Year東京大学大学院新領域創成科学研究科
Graduate School of Frontier Sciences, The University of Tokyo--- 国際協力学専攻 --Department of International Studies
修士課程一般入試 入学試験問題
Ordinary Examination for Master’s Course

専門科目 Specialized Subject
令和 3 年 8 月 17 日（火） August 17 (Tue), 2021
14:00－15:10（70 minutes）
注意事項 Instructions

1.

試験開始の合図があるまで、この問題冊子を開いてはいけません。
Do not open this booklet until you are instructed to do so.

2.

解答には、必ず黒色鉛筆（または黒色シャープペンシル）を使用しなさい。
Use a black pencil or a black mechanical pencil to write your answers.

3.

問題 1～問題 3 の 3 つの大問の中から 1 つだけを選択して答えなさい。2 つ以上の大問を解答した場合には、採点されない。
Choose only one of the following 3 Problems and answer all the questions for that Problem. If you answer more than one
Problem, your answers will not be given any scores.

4.

解答用紙・草稿用紙はそれぞれ１枚です。破損した場合を除き、解答用紙もしくは草稿用紙を 2 枚以上配布することはできません。
You have been provided 1 answer sheet and 1 draft sheet. Unless they are damaged, you may not exchange or request
additional sheets.

5.

解答用紙の所定欄に、受験番号・選択した問題番号（問題 1・問題 2・問題 3 のいずれか）を必ず記入しなさい。また、問題冊子・草稿用紙にも受験番号を記入しなさい。受験番号・問題番号が記入されていない場合には採点されない場合があります。
In the designated blanks on the answer sheet, fill in your Examinee’s number and the number of your question choice(Problem 1 - 3). Fill in your Examinee’s number in the designated blanks on the question booklet and the draft sheet aswell. If those are not filled in properly, your answers may not be scored.

6.

解答用紙に、解答に関係のない文字、記号、符号などを記入してはいけません。
Do not mark or make any irrelevant symbols or writings on your answer sheet.

7.

問題冊子・解答用紙・草稿用紙を持ち帰ってはいけません。
Do not take the question booklet, answer sheet, and draft sheet out of the room.

8.

試験時間は 70 分です。ただし、試験開始後 30 分を経過した後は、問題冊子・解答用紙・草稿用紙を試験監督に提出したうえで、退出してもかまいません。
The examination time is 70 minutes. You must remain in the room for at least 30 minutes once the examination starts.
When you leave, you must submit your question booklet, answer sheet, and draft sheet to the proctor.

このページは空白です。問題は次のページから始まります。
This is a blank page. The test starts from the next page.

問題１
養鶏は、途上国の小規模農家にとり、しばしば貴重な収入源となっている。しかし、鳥インフルエンザ等の感染症による大きな被害が生じることが時折ある。養鶏を対象とした感染症による被害に対する金融的保護について、下記の質問に答えなさい。

問１．保険は情報の非対称性の影響を受けやすいと言われる。保険市場が情報の非対称性により失敗するメカニズムを 300 字程度で説明しなさい。
問２．養鶏が被り得る感染症被害の不確実性の特徴を簡潔に説明しなさい。また、その不確実性に対応する際、途上国の小規模養鶏農家が直面する制約にはどのようなものがあるかも併せて説明しなさい。
問３．途上国の小規模養鶏農家を対象とした次の二つのスキームを比較、評価しなさい。
(a) 任意加入の養鶏保険(b) 当局による緊急補償スキーム
その際、実効的な補償範囲（対象、金額等）と財政的実行可能性に留意しなさい。

Problem 1
Although poultry farming in developing countries is often a precious sourceof income for small farming households, it can occasionally incur heavy losses
from infectious diseases such as bird flu. Answer the following questions on
financial protection for poultry farming against losses from infectious
diseases.

Question 1) Insurance is said to be prone to information asymmetry. In about
150 words explain how insurance markets fail because of information
asymmetry.
Question 2) Explain concisely the nature of uncertainty that poultry farming
may incur from losses due to infectious diseases. Also explain the various
constraints in coping with the uncertainty small poultry farming households
in developing countries may face.
Question 3) Compare and evaluate the following two schemes targeting small
poultry farming households in developing countries:(a) A voluntary poultry insurance scheme.
(b) An emergency compensation scheme by the authorities.
In so doing, pay attention to the effective coverage (targets, monetary payout,etc.) and issues related to financing of the schemes.

問題２
以下の問いに答えなさい。

問１．開発途上国の水や衛生(Water, Sanitation, and Hygiene)に関連する問題のうち、COVID-19 のパンデミック下においてより顕著となったとあなたが考える問題について、具体的な国または地域を挙げて説明しなさい。
問２．問 1 で回答した問題が未だに解決に至っていないことの要因として、①
当該国あるいは当該地域、および②外部機関（国際協力機関、援助国、企業等）が有するものとして何が考えられるか、それぞれについてあなたの考えを述べなさい。または、相互の問題として、合わせて回答しても良い。
問３．問 1 で回答した問題に対する解決策として、水や衛生関連の事業モデルをひとつ挙げ、それが持続的に成立する上で必要となる要件についてあなたの考えを述べなさい。

Problem 2
Answer the following questions.

Question 1) Given the COVID-19 pandemic situation, choose and explain awater, sanitation, and hygiene issue of a specific developing country or region,that in your opinion is likely to be more problematic for the local community.
Question 2) Consider the issue you addressed in Question 1 and discuss why
the problem remains unsolved. In so doing, consider ① the country or theregion and② external agencies such as international cooperation

organizations, donor countries, and private sectors, or consider theinteractions between ① and ②.
Question 3) Provide a project model that may solve the water, sanitation, andhygiene related issue you addressed in Question 1, and discuss the necessary
conditions to make the project model sustainable.

໰୊ 3໰1৽͍ٕ͠ज़ͷී‫ٴ‬աఔΛߟ͑Δɻ࣌ࠁ t ≥ 0 ʹ͓͍ͯͦͷٕज़Λར༻͍ͯ͠Δਓͷൺ཰Λ r(t) ͱ͢Δɻൺ཰ͷ࣌ؒมԽ͸ɺఆ਺ a > 0 Λ༻͍ͯdr(t) = ar(t){1 − r(t)}dt[1]ͱॻ͚Δͱ͢Δɻ(1) ্ड़ͷࣜ [1] ͕drdt (t)r(t){1 − r(t)}=a[2]ͱॻ͚Δ͜ͱΛ༻͍ͯɺ͜ͷղ r(t) Λ‫ٻ‬Ί͍ͨɻղ͕r(t) =1
1 + f (t)[3]ͱද͞ΕΔͱͯ͠ɺf (t) Λ‫ٻ‬ΊΑɻͳ͓ɺt = 0 ͷͱ͖ʹɺf (0) = A > 0 Ͱ͋Δͱ͢Δɻ(2) ͋Δ࣌ࠁ t ʹ͓͍ͯɺར༻։͔࢝Βͷ͕࣌ؒ s (t ≥ s ≥ 0) Ͱ͋Δਓͷີ౓෼෍ؔ਺Λ g(s; t)ͱ͢Δɻ૯ਓ‫͕ޱ‬ఆ਺ N Ͱ͋Δͱ͢Δͱɺඍখͳ ∆s ʹରͯ͠ɺར༻Λ։͔࢝ͯ͠Βͷ͕࣌ؒsʙs + ∆s Ͱ͋Δਓ਺͸ N g(s; t)∆s ͱ༩͑ΒΕΔɻ‫ݸ‬ਓ͸Ұ౓ͦͷٕज़Λར༻͠͸͡ΊͨΒɼར༻Λதࢭ͢Δ͜ͱ͸ͳ͍΋ͷͱͯ͠ɺ࣌ࠁ t ʹ͓͚Δ෼෍ؔ਺ g(s; t) Λɺࣜ [3] Ͱ༻͍ͨؔ਺ f Λ༻͍ͯදͤɻ

(3) ར༻ऀൺ཰ r ͷมԽ཰͕ɺ͋Δఆ਺ p > 0 Λ༻͍ͯɺdr(t) = ar(t){1 − r(t)} − pdt[4]ͱ༩͑ΒΕΔͱ͢Δɻp > 0 ͷͱ͖ͷ r(t) ͸ɺp = 0 ͷͱ͖ͱͲͷΑ͏ʹҟͳΔ͔Λఆੑతʹઆ໌ͤΑɻ(4) ৽ٕज़ͷී‫ʹٴ‬Ө‫͢ڹ‬Δཁૉͱͯ͠ɺࣜ [4] ͷ p ͱͯ͠ߟྀͰ͖Δ΋ͷΛҰͭ‫͛ڍ‬Αɻ·ͨɺͦͷཁૉͷӨ‫ڹ‬Λߟྀͭͭ͠ɺ͜ͷٕज़ͷී‫ٴ‬Λଅ͢ઓུΛఏҊͤΑɻʢ࣍ทʹଓ͘ʣ໰2͋ΔԽֶංྉͷ੒෼ A ʹ੒෼ B Λࠞ߹ͤ͞Δ͜ͱʹΑΓɺ୯Ґ໘ੵ͋ͨΓͷੜ࢈ྔ y ͕มΘΔɻ

AͱBΛ1−x:x(0 ≤ x ≤ 1) ͷൺ཰Ͱࠞ߹ͨ͠ͱ͖ͷɺ୯Ґ໘ੵ͋ͨΓͷੜ࢈ྔ y ͸ɺ
y = 4x(1 − x)[5]Ͱ༩͑ΒΕΔɻ͔͠͠ɺௐࠪ࣌఺Ͱ͸͜ͷࣄ࣮͸஌ΒΕ͍ͯͳ͍ɻ
ͦ͜Ͱɺ༷ʑͳখ‫ن‬໛ଜམͰௐࠪ͢Δ͜ͱͱͳͬͨɻͦͷࡍɺx ͱ y ͷؔ܎ͱͯ͠ɺఆ਺ a Λ༻͍ͯ

y = ax[6]ΛԾఆͯ͠෼ੳ͢Δ΋ͷͱ͢Δɻ(1) ࣜ [5] ͷΑ͏ͳඇઢ‫ܗ‬ੑΛ༗͢Δؔ܎ੑΛɺࣜ [6] ͷΑ͏ͳࣜͰۙࣅ͢Δ͜ͱͷϝϦοτ͓ΑͼσϝϦοτΛड़΂Αɻ(2) x ͕ [0, 1] ͷൣғͰ‫ۉ‬Ұʹ෼෍͢Δͱ͢Δͱɺa ͷ஋͸͍ͭͩ͘ͱਪఆ͞ΕΔ͔ɻ(3) ධՁ‫ࠩޡ‬Λখ͘͢͞Δ͜ͱΛߟ͑ɺ෼ੳʹ༻͍Δࣜ [6] ʹఆ਺߲ b Λಋೖͯ͠y = ax + b[7]ͱ͢Δɻ͜ͷͱ͖ͷ໰୊఺΍ͦͷ໰୊Λճආ͢ΔͨΊʹཹҙ͢΂͖఺ʹ͍ͭͯड़΂Αɻ(4) ֤ଜམͰಘΒΕΔσʔλ਺͸ 10ʙ20 ఔ౓ͱগͳ͘ɺͻͱͭͷଜམ಺Ͱ͸΄ͱΜͲͷੈଳ͕ಉ͡Α͏ͳ஋ͷ x Λ༻͍͍ͯΔɽଜམ͝ͱʹμϛʔม਺Λಋೖͯ͠෼ੳ͢Δͱ͢Δɻ͜ͷͱ͖ͷ෼ੳ݁Ռʹ͸ͲͷΑ͏ͳ໰୊͕͋Γ͑Δ͔Λઆ໌ͤΑɻ

ʢ໰୊ 3 ऴΘΓʣProblem 3Question 1We consider a diffusion process of a new technology. Let r(t) denote the ratio of the people
who are using the technology at time t. Temporal change of the ratio r(t) is given asdr(t) = ar(t){1 − r(t)}dt[1]where a is a constant.
(1) We want to obtain r(t) considering that equation [1] can be written as
drdt (t)r(t){1 − r(t)}

= a.

[2]

We write the solution r(t) in the form as follows.
r(t) =1
1 + f (t)[3]Obtain f (t), assuming that f (0) = A > 0 at time t = 0.
(2) Let g(s; t) denote a density distribution function, at time t, of people whose elapsed time
is s (t ≥ s ≥ 0) after starting to use the technology. If the total population is given by aconstant N , the number of people who have been using the new technology for the time s∼ s + ∆s, is given as N g(s; t)∆s for infinitesimal ∆s. Assuming that once a person starts
using the technology, he/she will not stop using it, write the density distribution functiong(s; t) using function f from [3].
(3) Suppose temporal change in the ratio of the adopters is given as
dr(t) = ar(t){1 − r(t)} − pdt[4]where p > 0 is a constant. Explain qualitatively the difference of the function r(t) whenp > 0 and when p = 0.
(4) Write one of the factors that affect the diffusion of new technology and can be considered
as p in the equation [4]. Considering the factor, propose a strategy to promote the diffusionof the technology.

(Continued on the next page.)Question 2
By adding constituent B to constituent A of a chemical fertilizer, the productivity per unit
space, y, changes. When A and B are mixed with the ratio of 1 − x : x
productivity per unit space, y, is given as(0 ≤ x ≤ 1), they = 4x(1 − x).

[5]However, the relationship of equation [5] is not known at the time of our survey.
We conduct the survey in various small villages. We analyze the data assuming the relationshipof x and y as
y = ax[6]

where a is a constant.
(1) What are the advantages and disadvantages to approximate the nonlinear relationship as
given in equation [5] by the linear relationship as given in equation [6].
(2) What should the value of a be, if x is uniformly distributed in the range [0, 1]?
(3) In order to reduce the evaluation error, we modify equation [6] and add another constantb.

y = ax + b.

[7]

What would be the problems and how might we avert such problems?
(4) We can collect only 10 to 20 samples in each village. Most households in a particularvillage use similar values of x. Suppose we analyze using village dummy variables. Explain
possible problems in the results obtained by our analysis.

(End of Problem 3)