2012: Vol. 36, Núm. 1
http://hdl.handle.net/2099/13226
2024-03-29T12:38:05ZAnalysing visual receptive fields through generalised additive models with interactions
http://hdl.handle.net/2099/13297
Analysing visual receptive fields through generalised additive models with interactions
Rodríguez Álvarez, María Xosé; Cadarso-Suárez, Carmen; González, Francisco
Visual receptive fields (RFs) are small areas of the visual fie
ld where a stimulus induces a re-
sponses of a particular neuron from the visual system. RFs ca
n be mapped using reverse cross-
correlation technique, which produces raw matrices contai
ning both spatial and temporal informa-
tion about the RF. Though this technique is frequently used i
n electrophysiological experiments,
it does not allow formal comparisons between RFs obtained un
der different experimental condi-
tions. In this paper we propose the use of Generalised Additi
ve Models (GAM) including com-
plex interactions, to obtain smoothed spatio-temporal ver
sions of RFs. Moreover, the proposed
methodology also allow for the statistical comparisons of t
he RFs obtained across various experi-
mental conditions. Data analysed here derive from studies o
f neurons’ activity in the visual cortex
of behaving monkeys. Our results suggest that the GAM-based
technique proposed in this paper
can be a flexible and powerful tool for assessing receptive fie
ld properties
2013-05-09T14:56:57ZRodríguez Álvarez, María XoséCadarso-Suárez, CarmenGonzález, FranciscoVisual receptive fields (RFs) are small areas of the visual fie
ld where a stimulus induces a re-
sponses of a particular neuron from the visual system. RFs ca
n be mapped using reverse cross-
correlation technique, which produces raw matrices contai
ning both spatial and temporal informa-
tion about the RF. Though this technique is frequently used i
n electrophysiological experiments,
it does not allow formal comparisons between RFs obtained un
der different experimental condi-
tions. In this paper we propose the use of Generalised Additi
ve Models (GAM) including com-
plex interactions, to obtain smoothed spatio-temporal ver
sions of RFs. Moreover, the proposed
methodology also allow for the statistical comparisons of t
he RFs obtained across various experi-
mental conditions. Data analysed here derive from studies o
f neurons’ activity in the visual cortex
of behaving monkeys. Our results suggest that the GAM-based
technique proposed in this paper
can be a flexible and powerful tool for assessing receptive fie
ld propertiesA comparison of some confidence intervals for estimating the population coefficient of variation: a simulation study
http://hdl.handle.net/2099/13289
A comparison of some confidence intervals for estimating the population coefficient of variation: a simulation study
Gulhar, Monika; Golam Kibria, B.M.; Albatineh, Ahmed; Ahmed, Nasar U
This paper considers several confidence intervals for estim
ating the population coefficient of
variation based on parametric, nonparametric and modified m
ethods. A simulation study has been
conducted to compare the performance of the existing and new
ly proposed interval estimators.
Many intervals were modified in our study by estimating the va
riance with the median instead
of the mean and these modifications were also successful. Dat
a were generated from normal,
chi-square, and gamma distributions for CV = 0.1, 0.3, and 0.
5. We reported coverage probability
and interval length for each estimator. The results were app
lied to two public health data: child
birth weight and cigarette smoking prevalence. Overall, go
od intervals included an interval for
chi-square distributions by McKay (1932), an interval esti
mator for normal distributions by Miller
(1991), and our proposed interval
2013-05-07T15:40:28ZGulhar, MonikaGolam Kibria, B.M.Albatineh, AhmedAhmed, Nasar UThis paper considers several confidence intervals for estim
ating the population coefficient of
variation based on parametric, nonparametric and modified m
ethods. A simulation study has been
conducted to compare the performance of the existing and new
ly proposed interval estimators.
Many intervals were modified in our study by estimating the va
riance with the median instead
of the mean and these modifications were also successful. Dat
a were generated from normal,
chi-square, and gamma distributions for CV = 0.1, 0.3, and 0.
5. We reported coverage probability
and interval length for each estimator. The results were app
lied to two public health data: child
birth weight and cigarette smoking prevalence. Overall, go
od intervals included an interval for
chi-square distributions by McKay (1932), an interval esti
mator for normal distributions by Miller
(1991), and our proposed intervalComparing and calibrating discrepancy measures for Bayesian model selection
http://hdl.handle.net/2099/13288
Comparing and calibrating discrepancy measures for Bayesian model selection
Horra, Julián de la; Rodríguez-Bernal, María Teresa
Different approaches have been considered in the literatur
e for the problem of Bayesian model
selection. Recently, a new method was introduced and analys
ed in De la Horra (2008) by
minimizing the posterior expected discrepancy between the
set of data and the Bayesian model,
where the chi-square discrepancy was used. In this article,
several discrepancy measures are
considered and compared by simulation, and it is obtained th
at the chi-square discrepancy is
reasonable to use. Then, an easy method for calibrating disc
repancies is proposed, and the
behaviour of this approach is studied on simulated data. Fin
ally, a set of real data is analysed
2013-05-07T15:39:31ZHorra, Julián de laRodríguez-Bernal, María TeresaDifferent approaches have been considered in the literatur
e for the problem of Bayesian model
selection. Recently, a new method was introduced and analys
ed in De la Horra (2008) by
minimizing the posterior expected discrepancy between the
set of data and the Bayesian model,
where the chi-square discrepancy was used. In this article,
several discrepancy measures are
considered and compared by simulation, and it is obtained th
at the chi-square discrepancy is
reasonable to use. Then, an easy method for calibrating disc
repancies is proposed, and the
behaviour of this approach is studied on simulated data. Fin
ally, a set of real data is analysedDecision-making techniques with similarity measures and OWA operators
http://hdl.handle.net/2099/13279
Decision-making techniques with similarity measures and OWA operators
Merigó, José M.; Gil-Lafuente, Anna M.
We analyse the use of the ordered weighted average (OWA) in de
cision-making giving special
attention to business and economic decision-making proble
ms. We present several aggregation
techniques that are very useful for decision-making such as
the Hamming distance, the adequacy
coefficient and the index of maximum and minimum level. We sug
gest a new approach by using
immediate weights, that is, by using the weighted average an
d the OWA operator in the same
formulation. We further generalize them by using generaliz
ed and quasi-arithmetic means. We
also analyse the applicability of the OWA operator in busine
ss and economics and we see that we
can use it instead of the weighted average. We end the paper wi
th an application in a business
multi-person decision-making problem regarding producti
on management
2013-05-03T16:43:28ZMerigó, José M.Gil-Lafuente, Anna M.We analyse the use of the ordered weighted average (OWA) in de
cision-making giving special
attention to business and economic decision-making proble
ms. We present several aggregation
techniques that are very useful for decision-making such as
the Hamming distance, the adequacy
coefficient and the index of maximum and minimum level. We sug
gest a new approach by using
immediate weights, that is, by using the weighted average an
d the OWA operator in the same
formulation. We further generalize them by using generaliz
ed and quasi-arithmetic means. We
also analyse the applicability of the OWA operator in busine
ss and economics and we see that we
can use it instead of the weighted average. We end the paper wi
th an application in a business
multi-person decision-making problem regarding producti
on managementIntroducing migratory flows in life table construction
http://hdl.handle.net/2099/13278
Introducing migratory flows in life table construction
Pavía, Jose M.; Morillas, Francisco; Lledó, Josep
The purpose of life tables is to describe the mortality behav
iour of particular groups. The
construction of general life tables is based on death statis
tics and census figures of resident
populations under the hypothesis of closed demographic sys
tem. Among other assumptions, this
hypothesis implicitly assumes that entries (immigrants) a
nd exits (emigrants) of the population
are usually not significant (being almost of the same magnitu
de for each age compensating each
other). This paper theoretically extends the classical sol
ution to open demographic systems and
studies the impact of this hypothesis in constructing a life
table. In particular, using the data of
residential variations made available to the public by the S
panish National Statistical Office (INE,
Instituto Nacional de Estad
́
ıstica) to approximate migratory flows, we introduce in the p
rocess of
constructing a life table these flows and compare, before and
after graduation, the crude mortality
rates and the adjusted death probabilities obtained when mi
gratory flows are, and are not, taken
into account
2013-05-03T16:41:30ZPavía, Jose M.Morillas, FranciscoLledó, JosepThe purpose of life tables is to describe the mortality behav
iour of particular groups. The
construction of general life tables is based on death statis
tics and census figures of resident
populations under the hypothesis of closed demographic sys
tem. Among other assumptions, this
hypothesis implicitly assumes that entries (immigrants) a
nd exits (emigrants) of the population
are usually not significant (being almost of the same magnitu
de for each age compensating each
other). This paper theoretically extends the classical sol
ution to open demographic systems and
studies the impact of this hypothesis in constructing a life
table. In particular, using the data of
residential variations made available to the public by the S
panish National Statistical Office (INE,
Instituto Nacional de Estad
́
ıstica) to approximate migratory flows, we introduce in the p
rocess of
constructing a life table these flows and compare, before and
after graduation, the crude mortality
rates and the adjusted death probabilities obtained when mi
gratory flows are, and are not, taken
into account