Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Disentangling collective trends from local dynamics   A single social phenomenon (such as crime, unemployment or birth rate) can be
observed through temporal series corresponding to units at different levels
(cities, regions, countries...). Units at a given local level may follow a
collective trend imposed by external conditions, but also may display
fluctuations of purely local origin. The local behavior is usually computed as
the difference between the local data and a global average (e.g. a national
average), a view point which can be very misleading. We propose here a method
for separating the local dynamics from the global trend in a collection of
correlated time series. We take an independent component analysis approach in
which we do not assume a small unbiased local contribution in contrast with
previously proposed methods. We first test our method on synthetic series
generated by correlated random walkers. We then consider crime rate series (in
the US and France) and the evolution of obesity rate in the US, which are two
important examples of societal measures. For crime rates, the separation
between global and local policies is a major subject of debate. For the US, we
observe large fluctuations in the transition period of mid-70's during which
crime rates increased significantly, whereas since the 80's, the state crime
rates are governed by external factors and the importance of local
specificities being decreasing. In the case of obesity, our method shows that
external factors dominate the evolution of obesity since 2000, and that
different states can have different dynamical behavior even if their obesity
prevalence is similar.

15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom