# Tagged Questions

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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### Data under detection limits for regressors in logistic regression

How could I handle left censored data (under detection limits) in a variable that I want to use as a regressor in logistic regression? What's is the best approach?
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### right or interval censored survival curve for survival within a survey period

I was hoping somebody could help with a relatively easy survival analysis question. I have survey data of an animal populaton and I want to create a survival curve for a specific year. So, I have ...
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### Estimating a rate of failure/survival using only right censored data?

I am trying to estimate the probability $q$ that a household with certain known covariates will move to a new home in the following year, by estimating an event rate $\lambda$ dependending on some ...
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### May I use a censored regression model for a truncated variable?

I am dealing with a truncated dependent variable (i.e.speed). To operationalise this variable I computed the months to take an action after an event. Then I normalised this value by dividing it for ...
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### A time-series analysis problem

I am trying to run an analysis where I am looking at the time it takes for a building lot to go from having submitted its first construction job application to having earned its first construction ...
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### Evaluate various censored estimators goodness-of-fit with and without ground truth

I would like to evaluate the goodness-of-fit for non-parametric estimators (Kaplan-Meier, Nelson-Aalen and their smoothed variations) of the survival function on a number of datasets. For some of them,...
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### Need help understand likelihood in survival analysis

I really appreciate it if you could help me understand the likelihood in a survival model with a time varying covariate. To be more clear, let's first start with a survival analysis with fixed ...
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### Maximum likelihood of gaussian with right censoring

I'm trying to fit the mean $\mu$ of right-censored gaussian data ($n$ samples) in a toy example (let's assume $\sigma^2=1$ is known), and the censoring happens always at the same value $s$. As far as ...
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### Poisson regression for ordered variables

I have three waves of data, and I am trying to estimate group-based trajectories of binge drinking across the three waves. The question asked (at all three waves was): “Over/During the past 12 months, ...
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### Fitting and comparing distributions based on diverse summary statistics

I have a bunch of samples, about 35, drawn from a fat-tailed distribution. I think it is reasonable to assume that the samples are all drawn from distributions from the same distributional family, ...
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### Right & Left data censoring

I have question regarding Data Censoring Methods. Is there any link where I can find details about Left and Right Censoring? Also does anyone have any clue of Articles where someone tried to merge ...
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### Combining monthly distributions of data with different right-censoring levels for prediction

I have a number of pricing datasets with integer values (prices in round dollars) for the same product which are right-censored at different levels (one level per dataset). I would like to combine ...
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### Random right cenoring

I observe a series of values from different trials ($Y_1, ... Y_N$). All values come from the same distribution ($F(\cdot)$). Trials do not have the same number of values ($N$ differs across trials)....
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### What to do with data that are bimodal at two tails of the distribution?

I am in a weird position where I prespecified a plan to use linear regression to analyze my data, and stated I would use transformations to address any assumption violations. I'm pretty certain my ...
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### How to fit a distribution of censored data? [duplicate]

I have a right censored data set and want to fit a distribution to my observations. How does maximum likelihood estimation work on censored data and are there any issues that I need to consider?
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### Survival analysis with multiple factors

I want to do survival analysis in a situation where I expect the survival time depends on two factors: Environment. Each person is in one of three environments, $E_1,E_2,E_3$. I expect that the ...
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### Variance-Covariance matrix of Weibull Distribution for right-censored data

The probability distribution function, cumulative distribution function and survival function of Weibull distribution are given by respectively, f(t;\alpha, \beta)= \dfrac{\beta}{\...
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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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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 ...