342 research outputs found
Learning Temporal Alignment Uncertainty for Efficient Event Detection
In this paper we tackle the problem of efficient video event detection. We
argue that linear detection functions should be preferred in this regard due to
their scalability and efficiency during estimation and evaluation. A popular
approach in this regard is to represent a sequence using a bag of words (BOW)
representation due to its: (i) fixed dimensionality irrespective of the
sequence length, and (ii) its ability to compactly model the statistics in the
sequence. A drawback to the BOW representation, however, is the intrinsic
destruction of the temporal ordering information. In this paper we propose a
new representation that leverages the uncertainty in relative temporal
alignments between pairs of sequences while not destroying temporal ordering.
Our representation, like BOW, is of a fixed dimensionality making it easily
integrated with a linear detection function. Extensive experiments on CK+,
6DMG, and UvA-NEMO databases show significant performance improvements across
both isolated and continuous event detection tasks.Comment: Appeared in DICTA 2015, 8 page
Measuring customer loyalty using an extended RFM and clustering technique
Today, the ability to identify the profitable customers, creating a long-term loyalty in them and expanding the existing relationships are considered as the key and competitive factors for a customer-oriented organization. The prerequisite for having such competitive factors is the presence of a very powerful customer relationship management (CRM). The accurate evaluation of customers’ profitability is considered as one of the fundamental reasons that lead to a successful customer relationship management. RFM is a method that scrutinizes three properties, namely recency, frequency and monetary for each customer and scores customers based on these properties. In this paper, a method is introduced that obtains the behavioral traits of customers using the extended RFM approach and having the information related to the customers of an organization; it then classifies the customers using the K-means algorithm and finally scores the customers in terms of their loyalty in each cluster. In the suggested approach, first the customers’ records will be clustered and then the RFM model items will be specified through selecting the effective properties on the customers’ loyalty rate using the multipurpose genetic algorithm. Next, they will be scored in each cluster based on the effect that they have on the loyalty rate. The influence rate each property has on loyalty is calculated using the Spearman’s correlation coefficient
On the Value of Out-of-Distribution Testing: An Example of Goodhart's Law
Out-of-distribution (OOD) testing is increasingly popular for evaluating a
machine learning system's ability to generalize beyond the biases of a training
set. OOD benchmarks are designed to present a different joint distribution of
data and labels between training and test time. VQA-CP has become the standard
OOD benchmark for visual question answering, but we discovered three troubling
practices in its current use. First, most published methods rely on explicit
knowledge of the construction of the OOD splits. They often rely on
``inverting'' the distribution of labels, e.g. answering mostly 'yes' when the
common training answer is 'no'. Second, the OOD test set is used for model
selection. Third, a model's in-domain performance is assessed after retraining
it on in-domain splits (VQA v2) that exhibit a more balanced distribution of
labels. These three practices defeat the objective of evaluating
generalization, and put into question the value of methods specifically
designed for this dataset. We show that embarrassingly-simple methods,
including one that generates answers at random, surpass the state of the art on
some question types. We provide short- and long-term solutions to avoid these
pitfalls and realize the benefits of OOD evaluation
Selective Mixup Helps with Distribution Shifts, But Not (Only) because of Mixup
Mixup is a highly successful technique to improve generalization of neural
networks by augmenting the training data with combinations of random pairs.
Selective mixup is a family of methods that apply mixup to specific pairs, e.g.
only combining examples across classes or domains. These methods have claimed
remarkable improvements on benchmarks with distribution shifts, but their
mechanisms and limitations remain poorly understood.
We examine an overlooked aspect of selective mixup that explains its success
in a completely new light. We find that the non-random selection of pairs
affects the training distribution and improve generalization by means
completely unrelated to the mixing. For example in binary classification, mixup
across classes implicitly resamples the data for a uniform class distribution -
a classical solution to label shift. We show empirically that this implicit
resampling explains much of the improvements in prior work. Theoretically,
these results rely on a regression toward the mean, an accidental property that
we identify in several datasets.
We have found a new equivalence between two successful methods: selective
mixup and resampling. We identify limits of the former, confirm the
effectiveness of the latter, and find better combinations of their respective
benefits
Soccer event detection via collaborative multimodal feature analysis and candidate ranking
This paper presents a framework for soccer event detection through collaborative analysis of the textual, visual and aural modalities. The basic notion is to decompose a match video into smaller segments until ultimately the desired eventful segment is identified. Simple features are considered namely the minute-by-minute reports from sports websites (i.e. text), the semantic shot classes of far and closeup-views (i.e. visual), and the low-level features of pitch and log-energy (i.e. audio). The framework demonstrates that despite considering simple features, and by averting the use of labeled training examples, event detection can be achieved at very high accuracy. Experiments conducted on ~30-hours of soccer video show very promising results for the detection of goals, penalties, yellow cards and red cards
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