Otdfbt

This rather old article argues about EU countries actual influence within the EU:

Germany is over-represented in the European Parliament, giving it a
correspondingly high potential to influence EU policies, while other
countries are at disadvantage, according to a recent report by a
Romanian think-tank. EURACTIV Romania reports.

Qvorum, a non-partisan think-tank which aims to stimulate citizens’
and social partners’ involvement in the policymaking process,
discovered that a number of countries have won privileged
representation in the assembly’s governing bodies, while other nations
are clearly under-represented.

Ten years have passed and I expect things to have changed. I am wondering if there is a more recent influence related article.

However, I am mainly interested in the causes of this difference in "influence". I expect that some objective facts such as population or GDP to be an important factor in influencing the number of representatives within an EU structure.

Question: How is number of representatives within EU structures computed?

Note: you can see Article 15 of the TEU for the European Council, Article 19 for the Court of Justice, and different sections of the TFEU for the European Central Bank and the Court of Auditors. It's fairly straightforward since it mostly requires a representative by member plus a president (or other similar positions). As so I'll focus on this answer on the EU parliament which has more complex (and "flexible") rules.

The allocation (apportionment) of seats in the EU parliament is decided by treaty following the rules exposed in Article 14 of the Treaty on European Union. Furthermore the actual composition is decided by the European Council.

Article 14

1. The European Parliament shall, jointly with the Council, exercise legislative and budgetary functions. It shall exercise functions of
   political control and consultation as laid down in the Treaties. It
   shall elect the President of the Commission.




2. The European Parliament shall be composed of representatives of the Union's citizens. They shall not exceed seven hundred and fifty in
   number, plus the President. Representation of citizens shall be
   degressively proportional, with a minimum threshold of six members per
   Member State. No Member State shall be allocated more than ninety-six
   seats. The European Council shall adopt by unanimity, on the
   initiative of the European Parliament and with its consent, a decision
   establishing the composition of the European Parliament, respecting
   the principles referred to in the first subparagraph.




3. The members of the European Parliament shall be elected for a term of five years by direct universal suffrage in a free and secret
   ballot.




4. The European Parliament shall elect its President and its officers from among its members.

To give a more practical example. Last year the European Council decided on the new rules of the parliament composition after the UK left the EU. The rules they choose are these:

Article 1

In the application of Article 14(2) TEU, the following principles
shall be respected:

– the allocation of seats in the European Parliament is to fully
utilise the minimum and maximum thresholds per Member State set by the
TEU in order to reflect as closely as possible the sizes of the
respective populations of the Member States,

– degressive proportionality is to be defined as follows: the ratio
between the population and the number of seats of each Member State
before rounding to whole numbers is to vary in relation to their
respective populations in such a way that each Member of the European
Parliament from a more populous Member State represents more citizens
than each Member of the European Parliament from a less populous
Member State and, conversely, that the larger the population of a
Member State, the greater its entitlement to a large number of seats
in the European Parliament,

– the allocation of seats in the European Parliament is to reflect
demographic developments in the Member States

Just as a curiosity this would be the new allocation of seats in the EU parliament.

NOTE: this will likely not be followed considering the latest developments on Brexit. It's in this answer for illustration purposes only.

EDIT: In the web page EU institutions and bodies in brief you'll find the list of the several institutions within the EU. Some of those only have sparse influence on policy. I will not describe the selection process for all of those bodies but that document should put you on the right track should you wish to do so. Most of this answer will focus instead on the EU parliament with pointers to other EU major institutions.

In any case the list of bodies and institutions is the following:

• European Parliament




• European Council




• Council of the European Union




• European Commission




• Court of Justice of the European Union (CJEU)




• European Central Bank (ECB)




• European Court of Auditors (ECA)




• European External Action Service (EEAS)




• European Economic and Social Committee (EESC)




• European Committee of the Regions (CoR)




• European Investment Bank (EIB)




• European Ombudsman




• European Data Protection Supervisor (EDPS)




• Interinstitutional bodies

For legislation (which I believe are the more relevant to your question since it directly relates to policy):

Law-making There are 3 main institutions involved in EU legislation:

• the European Parliament, which represents the EU’s citizens and is directly elected by them;




• the Council of the European Union, which represents the governments of the individual member countries. The Presidency of the Council is
  shared by the member states on a rotating basis.




• the European Commission, which represents the interests of the Union as a whole.

For administration:

Two other institutions play vital roles:

• the Court of Justice of the EU upholds the rule of European law




• the Court of Auditors checks the financing of the EU's activities.

Interinstitutional bodies:

The EU has a number of other institutions and interinstitutional
bodies that play specialised roles:

• the European Central Bank is responsible for European monetary policy




• the European External Action Service (EEAS) assists the High Representative of the Union for Foreign Affairs and Security Policy,
  currently Federica Mogherini. She chairs the Foreign Affairs Council
  and conducts the common foreign and security policy, also ensuring the
  consistency and coordination of the EU's external action.




• the European Economic and Social Committee represents civil society, employers and employees




• the European Committee of the Regions represents regional and local authorities




• the European Investment Bank finances EU investment projects and helps small businesses through the European Investment Fund




• the European Ombudsman investigates complaints about maladministration by EU institutions and bodies




• the European Data Protection Supervisor safeguards the privacy of people’s personal data




• the Publications Office publishes information about the EU




• the European Personnel Selection Office recruits staff for the EU institutions and other bodies




• the European School of Administration provides training in specific areas for members of EU staff




• a host of specialised agencies and decentralised bodies handle a range of technical, scientific and management tasks

Furthermore you have positions related to smaller offices, or within EU political parties (which keep coming and going and almost certainly chose their own rules of selection).

For the EC and the ECJ, the rule is straightforward: it's one appointment per member state.

For the EP, the general idea is to give similar representation to each country based on their population, with two twists:

• Early on, smaller countries got a few bonus seats so larger countries (Germany, France, Italy at the time) couldn't simply band together and push them around. These bonus seats stuck around over time. (This is similar in spirit to what the Bundesrat does and it is called degressive proportionality.)




• For political reasons, countries of similar size have traditionally been given the same number of seats. For instance France, Italy, and the UK (until 2014, when France got a bonus seat); or Spain and Poland; and so forth.

As to who chairs committees and the like, which is what the article seems to be looking at, what the whining is about beggars belief. The US equivalent would be to complain that CA, NY, FL, and TX are overrepresented in the US House. But that should come as no surprise given that they've more Reps to begin with. Who gets what seat in EP committees and such depends on how the MEPs want to manage their sausage factory. It simply happens that, as the most populous EU member, Germany also has the most MEPs. And in contrast with the UK and France for instance, they don't have a large swath of EU skeptics in a parliament controlled by a non-extremist coalition.