Archive for the ‘Curious’ Category

How does Germany compare to the USA in terms of median income?

Friday, May 13th, 2016

Article with the surprising claim that the median income in Germany is lower than that in most US states, when PPP adjusted –

Conclusion: I would say the weak points that bear more looking at are whether the household adjustment (the square root mentioned above) is significant, and also whether if there are net transfer payments that it’s really not an expense, but rather a form of savings, in which case it would be inaccurate to subtract net savings from the disposable income.


The original data linked to is where the income number that was used was the “median disposable income”, which was in 2012,

  1. 20857 EUR for Germany
  2. 30355 USD for the USA

The “Purchasing Power Parities for GDP and related indicators table” has National currency per US dollar as

  1. 0.786 EUR for Germany
  2. 1.000 USD for USA (by definition)

The exchange rate for the EUR, as obtained from ( was between 0.755436 and 0.813635, so not significantly different.

Dividing by PPP, then, we get

  1. 26536 for Germany
  2. 30355 for the USA


The definitions are in

The income unit is an individual, and there is this adjustment they make for household size which divides the income by the square root of the household size, instead of just dividing by household size. This has the effect of adjusting incomes up when households are larger. This is for the purposes of accounting for economies of scale.

The components of disposable income are

E: employee income, including wages and salaries, cash bonuses and gratuities, commissions and tips, directors’ fees, profit sharing bonuses and other forms of profit-related pay, shares offered as part of employee remuneration, free and subsidised goods and services from an employer, severance and termination pay.1 Sick pay paid by social security should also be included.

KI: capital and property income, including income from financial assets (net of expenses), income from non-financial assets (net of expenses) and royalties. Regular receipts from voluntary individual private pension plans and life insurance schemes should also be included in this income component.

SEI: income from self-employment, including profits and losses from unincorporated enterprises, as well as goods produced for own consumption (net of the costs of inputs). [The inclusion of this latter variable aims to adjust the OECD income concept to the realities of middle-income countries (such as Brazil, South Africa and others), where subsistence agriculture represents a significant income source for people at the bottom of the distribution. Countries that do not collect information on this income item should indicate so in the metadata sheet of the OECD questionnaire].

TRR: current transfers received, including transfers from social security (including accident and disability benefits, old-age cash benefits, unemployment benefits, maternity allowances, child and/or family allowances, all income-tested and means-tested benefits that are part of social assistance), transfers from employment related social insurance, as well as cash transfers from both non-profit institutions and other households

TRP: current transfers paid, including direct taxes on income and wealth, social security contributions paid by households, contributions to employment-related social insurance, current transfers paid to both other households and non-profit institutions. [Values for transfers paid should be reported in the OECD questionnaire with a negative sign].

which certainly looks like social welfare has been accounted for.

Conclusion: I would say the weak points that bear more looking at are whether the household adjustment (the square root mentioned above) is significant, and also whether if there are net transfer payments that it’s really not an expense, but rather a form of savings, in which case it would be inaccurate to subtract net savings from the disposable income.

Was the 2015-2016 flu vaccine spot-on?

Thursday, February 18th, 2016

The 2015-2016 trivalent flu vaccine protected against:

  • an A/California/7/2009 (H1N1)pdm09-like virus
  • an A/Switzerland/9715293/2013 (H3N2)-like virus
  • a B/Phuket/3073/2013-like virus. (This is a B/Yamagata lineage virus)

According to the latest Flu Express publication from the Taiwan CDC, the prevalent flus so far this season are:

  • A H1N1 (36.8%)
  • A H3N2 (63.2%)
  • B (25.2%)

Does this mean they got it completely right this year (for Taiwan at least)?

Approximate Dynamic Programming

Friday, May 4th, 2012

I am currently reading Approximate Dynamic Programming by Warren Powell. The book comes out of work that Powell did with Schneider National, a company that operates a large fleet of trucks in the US.

I haven’t gone very far in the book, but it definitely seems very promising. The central premise that I can grasp is that it is fruitful to consider the quality of a model strictly in light of the decisions that the model is being used to make. This can be contrasted with typical surrogates like the root mean squared error or mutual information – those measures for model quality are largely derived using definitions of convergence towards total knowledge, and attempting to reach the state of total knowledge is often futile in reality.

In building practical models with practical approximations, choices in the early steps of an analysis often contain implicit knowledge about what the output from those steps is to be used for. To carry this process to its logical conclusion would be what I imagine approximate dynamic programming accomplishes – this way of dealing with ignorance trades off uncertainties in such way as to minimize the impact they have on decision quality, as measured by what you actually care about for the specific problem.


Sunday, July 1st, 2007

I need help understanding this paragraph from The Economist:

His grim prediction is based on the “impossible trinity”: an economy cannot control domestic liquidity and manage its exchange rate if its capital account is open. If it holds down its currency, foreign-exchange inflows will boost money growth. The central bank can try to “sterilise” the impact of bigger reserves by selling securities to mop up the excess liquidity. The snag is that bond sales will tend to push up interest rates and so attract yet more capital inflows. Mr Roubini believes that the room for sterilisation by Asian central banks is severely limited and so rising reserves mean even greater excess liquidity.

Quantum Riddle

Tuesday, May 22nd, 2007

Question: Of the bound hydrogen atom eigenstates, which has the highest kinetic energy?

Answer: The lowest energy state.

Ain’t that curious? Kepler’s laws helped me understand this one. Oh, and this holds for all molecules – I leave the proof as an exercise.

State Counting in Thermodynamics

Saturday, March 3rd, 2007

Let’s say you have a box full of particles, and each of those particles is independently in one of N states. Each state has a probability of occuring. Let us further suppose that none of these probabilities are the same – if so, then there is one state with the highest probability. If there are then properties E and V which are diagonal and have a 1-1 correspondence to each other amongst all the states, then the most common E and most common V definitely are related to each other by E=MV^2/2.

Examine the Speed and Energy distributions of the ideal gas. The modal values of these two distributions do not correspond to each other via the E = MV^2/2 relation. Paradox?


Free Will

Thursday, February 22nd, 2007

In “Free Will – Even for Robots“, John McCarthy describes what he feels are the minimal criteria for a complex system to be considered as possessing free will, namely the ability to state “I can, but I won’t”.

The decision process of such an entity is divided into two phases, starting with the consideration of all possible actions, i.e. what it can do, and then further searching within that set for what it wants most to do. (more…)

Money and Zero-Sum games Part II

Wednesday, February 21st, 2007

Thanks to some very good points made by wakaba I’ve decided to write a followup post.

More cash is always worth more than less cash. Rationally trading two differing amounts of the same currency is thus impossible. A stock has risk; its future dividend is not guaranteed. Estimating the value of a stock involves constructing a probability distribution for the future stock dividends.

Different people have different information, and may thus infer different distributions. However, even when they have the same beliefs and infer the same distribution, they will still price the stock differently depending on their differing appetites for risk. For example, a grad student would be willing to pay less than a millionaire for the same 50% chance at winning $10,000. See also the St Petersburg Paradox.

A corollary of this line of logic: given that two people infer the same probability distribution A, they will arrive at the same price for the stock as the uncertainty of A becomes smaller and the appetite for risk becomes irrelevant.

Money and Zero-Sum games

Monday, February 12th, 2007

In a two-way barter trade, two people (1 and 2) exchange two objects (A and B). From the voluntary nature of the transaction, we conclude that both people value their new possessions more than their old; to one person A > B while to the other B > A. These two statements contradict each other, but that’s okay because they apply to different people; Person 1 prefers A to B while Person 2 prefers B to A. In fact, this contradiction is what makes trade possible. At this point, there is little temptation to label either person as being wrong.

Now imagine that prior to the trade, the two people had in fact just walked out of the same store, having bought the objects of the trade in the store. At best, if both objects cost the same, the trade seems pointless. In all other cases, one of the people could have done better by just paying less for his post-trade object in the store. This untaken better option prompts us to label the choice as irrational.


Hedge Funds and Insider Trading

Friday, October 20th, 2006


The NYT published an editorial today on how information available to hedge funds by virtue of their being involved with trading loan derivatives may effectively mean some kind of insider trading.

Insider trading is interesting because the definition of who is an insider has everything to do with game theory. On one hand, you want people to capitalize on information so that there is incentive to spread the information faster, resulting in higher efficiency. On the other hand, if few enough people know something to begin with, it becomes profitable to withhold that information and release it in a disruptive manner such as to reap maximum profit.