Handling Censoring and Censored Data in Survival Analysis: A Standalone Systematic Literature Review

Turkson, Anthony Joe; Ayiah-Mensah, Francis; Nimoh, Vivian

doi:10.1155/2021/9307475

Cited by 35 publications

(29 citation statements)

References 52 publications

(77 reference statements)

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“…S (t) must be, by definition, non-negative and non-increasing with time. The probabilities over time are presented by the survival curve, which gives the proportion of the initial population that survives after time t. One of the assets of the survival analysis is that features in a population that have not been subject to the time-to-event (appearance and disappearance) within the observational window are labeled as left-or right-censored and are taken into consideration during the construction of the survival curve (Leung et al 1997;Turkson et al 2021). There are several methods proposed for estimating the survival probability from survival times both censored and uncensored.…”

Section: Lifetimes Of Swirlsmentioning

confidence: 99%

Chromospheric swirls

Dakanalis

Tsiropoula

Tziotziou

et al. 2022

A&A

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Context. Chromospheric swirls are related to convectively driven vortex flows and considered to play a significant role in the dynamics and heating of the upper solar atmosphere. It is important to automatically detect and track them in chromospheric observations and determine their properties. Aims. We aim to detect and track chromospheric swirls both in space and time by applying a newly developed novel automated method on high quality time series of Hα observations and to conduct a statistical analysis to determine their properties. Methods. We applied a recently developed automated chromospheric swirl detection method to time-series observations of a quiet region of the solar chromosphere obtained in the Hα-0.2 Å wavelength of the Hα spectral line by the CRISP instrument at the Swedish 1-m Solar Telescope. The algorithm exploits the morphological characteristics of swirling events in high contrast chromospheric observations and results in the detection of these structures in each frame of the time series and their tracking over time. We conducted a statistical analysis to determine their various properties, including a survival analysis for deriving the mean lifetime. Results. A mean number of 146 ± 9 swirls was detected within the Hα-0.2 Å field of view at any given time. The mean surface density is found equal to ∼0.08 swirls Mm −2 and the occurrence rate is ∼10 −2 swirls Mm −2 min −1 . These values are much higher than those previously reported from chromospheric observations. The radii of the detected swirls range between 0.5 and 2.5 Mm, with a mean value equal to 1.3 ± 0.3 Mm, which is slightly higher than previous reports. The lifetimes range between 1.5 min and 33.7 min (equal to the duration of the observations) with an arithmetic mean value of ∼8.5 min. A survival analysis of the lifetimes, however, using the Kaplan-Meier estimator in combination with a parametric model results in a mean lifetime of 10.3 ± 0.6 min. Conclusions. Swirls are ubiquitous in the solar chromosphere. An automated method sheds more light on their abundance than visual inspection, while higher cadence, higher resolution observations will most probably result in the detection of a higher number of such features on smaller scales and with shorter lifetimes.

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Section: Lifetimes Of Swirlsmentioning

confidence: 99%

Chromospheric swirls

Dakanalis

Tsiropoula

Tziotziou

et al. 2022

A&A

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“…The use of the Kaplan-Meier estimator is conditioned by non-informative censoring ( Turkson, Ayiah-Mensah & Nimoh, 2021 ). Non-informative censoring includes two cases, which are non-prognostic and independent censoring ( Leung, Elashoff & Afifi, 1997 ).…”

Section: Survival Latency Methodsmentioning

confidence: 99%

General Internet service assessment by latency including partial measurements

Komosný¹

2022

PeerJ Computer Science

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Latency is one of the key parameters of Internet services. However, it is difficult to correctly assess a service by its latency. Many latency measurements are blocked en route by routers and firewalls. For this reason, the service latency is not fully known. This work proposes a method to assess Internet services including the blocked latency measurements. Survival theory is applied to process latency values. The results show that the omission of blocked latencies from statistical processing severely underestimates the service latency. Two Internet service providers were compared as an example. Their latency difference was 9 ms using the traditional approach. The survival latency resulted in a difference of 17 ms. The method of survival latency can be used to increase revenues in e-commerce and to improve the experience of online gaming.

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“…Insurers may also not compensate for the losses if the loss is below a certain value ("deductible"), designating the payable amount as "0." Censoring may be undertaken in clinical research to make conclusions on test results such as a blood test or any other test for a specific illness [9,10,14,17]. If the measured value is below a certain threshold, the values below the threshold are taken and reported as ≤ a specific value or any designated value including 0.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…In population studies, researchers may be interested only at the statistics of people earning salaries below a certain value, above a certain value, or in a specific range. In postoperative cancer chemotherapy studies, researchers may be interested in looking at the statistics of people living past 2 years (or some period) beyond surgery [9,10,17].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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Pedagogy of transformation of a random variable, censoring, and truncation of data

Shankar

2022

Comp Applic In Engineering

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The author has been incorporating data analytics into the probability course for students pursuing baccalaureate programs in engineering through weekly assignments and end‐of‐the‐term projects. Data analytics makes the probability course much more relevant to the current trends in business, industry, and medicine that rely on data. The discussion related to the coronavirus pandemic about missing and incomplete data, the inability to pinpoint the exact start of the disease, and so forth offered an opportunity to expand activities in data analytics by examining “truncation” and “censoring” of data. In simple terms, truncation implies the exclusion of data (either not collected or ignored) in a certain range. Censoring implies redefining the data in a certain range while keeping the rest of the original data. A demo was created to explore the association of the transformation of random variables (mixed and conditional) to censoring and truncation. The demo utilized the theory of random variables, simulation, and computational techniques to examine and establish the link between the mixed transformation of variables and censoring. A similar link of conditional transformation of variables to truncation was also seen. The demo was used as the basis for a weekly assignment to the students. The analysis and results suggest that it is possible to expand the scope of the course in engineering probability to provide training in contemporary topics in data analytics.

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Handling Censoring and Censored Data in Survival Analysis: A Standalone Systematic Literature Review

Cited by 35 publications

References 52 publications

Chromospheric swirls

Chromospheric swirls

General Internet service assessment by latency including partial measurements

Pedagogy of transformation of a random variable, censoring, and truncation of data

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