The process of censoring yields data w/ only partial information. The most common example of censoring is *right censoring* in survival analysis, where the time until the event occurred is only known to be longer than some duration because the event had not occurred when the study ended.

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how to quantify variation in continuous outcome for samples matched on continuous predictor

I have a data consisting of about 2 million cases. Cases are scored on some (overdispersed) predictor we'll call "employee performance." I would like to match or pool cases with the same score or ...
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14 views

Version of Mann-Whitney U test, for right-censored data

Is there an equivalent of the Mann-Whitney U test, but for right-censored data? I have right-censored numerical data from two different groups. The mean for one group is higher than the other. I'd ...
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36 views

Inventory Turnover Estimation

I have an inventory of real estate. Every period I am acquiring some new inventory and selling some items from the inventory. I would like to estimate the average waiting time it takes to sell an ...
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to estimate bj regression category by category

I'm studying linear regression model with censored data. ~ Buckley James Estimator. For example, I have a data set which contains groups (two categories; 1,2). I estimated bj regression category by ...
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19 views

Survival estimation goes crazy when I move all censored times to t=0

I have a simulated dataset with 1000 observations and Weibull-distributed survival time as outcome. A certain percentage $p_1$ of these guys belong to a risk group ($Z_i=1$ for risk group, $Z_i=0$ for ...
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Censored items in FERPA-compliant education data

I have open source data for K-12 educational performance. It is for North Carolina, at the individual school and subject level. It is conformant with FERPA regs, leading to my problem. It reports ...
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35 views

Sign and size of OLS bias for Tobit models

I have a question related to the sign and size of the OLS bias in the case of a Tobit model. Consider the following model (1) Sample of observations $\{X_i,Y_i\}_{i=1}^n$, i.i.d., $X_i$ is a vector ...
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28 views

Derivation of the censoring likelihood function? [duplicate]

The (right-) censoring of likelihood function is defined as: $$ L(\theta) = \prod_{i=1}^m f(x_i;\theta) \cdot \prod_{i=m+1}^n P_{\theta}(X_j>a) $$ where observations $x_i$, $i=1,...,m$ have ...
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43 views

Likelihood function for a Weibull model

I have an assignment for my course Microeconometrics. Currently I am stuck on the following question You are asked to help out with the statistics of a medical study. We are interested in the time ...
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97 views

Meaning of “missing by design” in longitudinal studies

I'm French and I'm reading an English book. I don't understand the term "when missingness is by design" — what does "by design" mean?
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18 views

non-parametric trend analysis with data that is both left and right censored

I am assessing the the presence of monotonic temporal trends in E. coli concentration data using a non-parametric approach. These data are both right and left censored (for example the lower detection ...
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1answer
41 views

Can a Cox proportional hazards model be used on general left-censored data (i.e. non-survival data)?

A familiar problem in applied science is having censored data, in particular left-censored data arising due to an assay or piece of equipment having a lower limit of detection (LOD). Assuming a ...
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235 views

Layman's explanation of censoring in survival analysis

I have read about what censoring is and how it needs to be accounted for in survival analysis but I would like to hear a less mathematical definition of it and a more intuitive definition (pictures ...
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15 views

Survival analysis: how are censored and non-censored patients dealt with and defined?

I have a pretty simple question. In a paper I am revising for a journal, there is a small survival analysis of patients. The study period starts on 1 March 2010 and ends on 1 June 2015. There are 70 ...
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24 views

KDE for censored data

I have a sample of observations where about $30\%$ of the observations are right-censored. I want to fit a kernel density estimator to this sample but I have not found a standard method to do so. Is ...
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26 views

How do I compute an average when one of the measurements couldn't be measured?

In my biology class we were doing a lab on respiration rates of peas. We used a respirometer with a small pipet tube (markings up to 1 mL) to measure the volume of gas; by immersing in water, the gas ...
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31 views

Need the formula and to understand the number needed to treat

I am reading the article http://www.ncbi.nlm.nih.gov/pubmed/16214598. I am having trouble with the calculation formula (to test it / reproduce it). The relevant information is in page 1282. For those ...
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14 views

Treatment of waiting time data with repeated observations for a finite time

A call center is open for 9 hours every day. My data are the times of occurrence of calls, divided in days. Some days are busier than the others and some days no calls at all occur. I have to estimate ...
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21 views

Right censored data, abundant in zeros for regression analysis

I am looking at conditioning to stimuli and there in the time taken to perform a certain task. The IV for this data is Conditioning periods ranging from 1-34 periods and the DV is the time taken for ...
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38 views

Dealing with Right Censored Data

I'm working with a dataset with n of roughly 300,000 and am trying to build a model to predict the time-to-event from multiple explanatory variables, including past times from the same subjects. ...
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46 views

Expected value of a censored poisson

I have the following density (it's a censored model): $$f(y) = \begin{cases} e^{-\lambda}(1+\lambda), & \text{if }y^*=0,1 \\ \frac{\lambda^{y^*}e^{-\lambda}}{y^*!}, & \text{if }y^*=2,3.... ...
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Uneven (right) censoring where the time of truncation is constant

I've collected data comparing the relative success of two different groups of participants on finding the answer to a difficult question. The problem is that not all the participants in the control ...
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43 views

Right-censored independent variable in Cox/logistic regression

I have a right-censored continuous independent variable that I want to include in a Cox regression. The variable is a physiologic test which is capped at a certain time, say 120 seconds, due to safety ...
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59 views

Censored Data Log Likelihood

Suppose we have a n random samples ($X_1,..., X_n$) from a negative exponential distribution. If lets say we have these n random samples are censored at t, such that ($X_1, ..., X_m$) are observed and ...
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competitive risk in propensity score matched cox regression

I am actually performing a survival analyse using propensity score matched cox regression. My outcome is calculated from biological data contained in a database. I censured each patient at the time ...
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30 views

censoring as a result of survey screening question

I have a survey data where respondents were asked if they or an immediate family member had previously used a lawyer and, for those who said yes, they were then asked if they had ever sued. I want to ...
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Censoring for events that don't occur

I have data on when the time between two events A and B. However, I am assuming if the time between them is more than 5 hours then the two events are unrelated and so we assume that on these occasions ...
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1answer
26 views

Counting total number of cells producing antibody in a 96-well plate using Poisson

I make cells produce an antibody. I then add cells to plates that contain 96 wells (random distribution). I know a cell is in a particular well because the well will be positive for the antibody. ...
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20 views

How to find the expected value of a random variable when it is observed only in a range?

I want to estimate an average livespan of a user account which is a time-difference in days between the account open and account closed. I observe the livespan of accounts that were closed before the ...
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2answers
40 views

How are censorings before the first event dealt with in survival analysis

If you have a dataset, sorted into ascending order by survival time (minimum of censoring and event time), and this dataset contains at least one censoring before the first event (so that the start of ...
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2answers
46 views

Inference for a distribution with different number of samples due to censoring

I have the following problem in case someone has an idea about how to solve this. Assume three experiments that refer to the same population for a random variable $X$. In the first experiment, I ...
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1answer
24 views

What is the justification? [duplicate]

I understand 'when' we right censore a survival time. But why do we do so? And how does it affect analysis in survival context. I would appreciate it anyone could recommend some reference.
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14 views

Does RMSE accurately represent performance for censored data?

I am working with some remotely sensed data collected at irregular intervals and want to use these observations to evaluate performance of a model. For each site location I have about 4-9 ground truth ...
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95 views

Probability density problem

Suppose that the random variable $X$ is uniformly distributed on the interval $[0,1]$ (i.e. $X \sim U(0,1)$) and suppose that $$Z=min(2,2X^2+1)$$ (a) Explain why $Z$ does not have a ...
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50 views

Handling survival data where people join at various stages

My question is about survival analysis. According to this censoring is a condition in which the value of a measurement or observation is only partially known. For example, suppose a study is ...
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27 views

Data censorship - simple reconstruction of missing data?

I have data from disease symptoms assessment on individuals (over time). Pattern of the disease is always a decreasing sigmoid, the disease starts with a 100% sound tissues, but ends up with a 0% ...
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1answer
17 views

How to average days until completion when some items haven't completed the cycle?

I am attempting to calculate the average number of days it takes for an order to go through our process - from receipt of order to delivery. When calculating the average days, how should I handle ...
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11 views

Handling a censored factor score?

I have an 11 item measure for which I am computing factor scores. It is a censored (floor effect) measure. EFA/CFA analysis indicates I should remove 3 of those items. Whether or not I remove those ...
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85 views

Should one use a censored survival model when an event is only observed at death?

A colleague of mine is trying to estimate how neutron radiation exposure changes cancer incidence rates (in mice). He has autopsy data that reports whether a cancer was observed at the time of death, ...
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52 views

WinBUGS - sample from the posterior of exponential distributed survival times

as introduction to WinBUGS, I want to simulate the posterior of the Gamma-Exp-Model. Because the posterior is known, I can varify the result. But the true posterior is always shifted to the right. I ...
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56 views

Handling Informative Censoring in Survival Analysis

In a survival study with informative censoring (for example, studying the effects of cigarettes on mortality and smokers are more likely to be Lost to Follow Up). This causes the censored data to be ...
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35 views

Kernel density estimation with censored data

I have several univariate data sets that I would like to fit with a Kernel density estimator. However, some of the data sets contain left, interval, and right censored observations. How can I ...
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140 views

How to estimate mean and variance of censored normal?

Supposing I have data which I know is normally distributed, but because the recording process is right censored, how do I estimate the parameters of the distribution?
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41 views

Censoring “Death” in Time-To-Recovery Analysis

I am performing time-to-recovery analysis comparing 2 groups. In both groups, a few subjects died from the disease under consideration (instead of recovering). Is it appropriate to consider the deaths ...
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126 views

How to simulate informative censoring in a Cox PH model?

I wish to simulate events from a Cox PH model where the censoring is informative, and to compare parameter estimator quality with estimates obtained from data generated by a Cox PH model with ...
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simulate censored data (right censored) using R statistics [duplicate]

I want to generate right censored data, but I want to be able to pass in a parameter to a function to dictate that a certain percentage of the data will be censored. I have found this R-package: ...
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Survival regression variance estimates

I would like help understanding why a survival regression with no censored data-points does not give the same variance estimates as a linear model (see code below). I think it must be something to do ...
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Heteroscedastic censored regression

I am dealing with a heteroscedastic censored dataset. I tried to use the survival analysis package in R to estimate a linear model for it. So before doing that, I conducted a simulation study, where I ...
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Some details in Cragg's Limited Dependent Variable article

1) Is there anybody who can explain me the precise meaning of the indices and hence, dimensions of the involved matrices of Cragg's equation (18) in his Limited Dependent Variables article from 1971? ...
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Cutoffs to consider for survival tree

In an tree based algorithm a criterion is measured at certain cutoffs for the variable. This cutoffs are the candidate split points for that variable. How does one come up with candidate split points ...