negative binomial

  1. M

    Modeling number of days in a clinic

    Hello guys, I wish to model the number of days patients stayed in a clinic. Some of my predictors included: type of injury/disease, age, insurance, etc. Since days are count data and my data is over-dispersed, negative binomial models seem to be the appropriate technique. However, I know that...
  2. J

    Estimating a negative binomial curve, from sample size and mean

    Hey guys! Apologies for the potentially *stupid* question... I'm *very* rusty on my maths and am not getting anywhere with Google's support. I'm a marketeer, looking at how/if it may be possible to estimate a NBD curve from a limited dataset... my client has given me some 'data' about...
  3. M

    Can data be classified as count data?

    Hi, I have a dataset spanning two years which consists of individuals entering some process. Once they have entered this process I want to predict the number of days they will remain in this process based on some set of covariates. There are some charateristics of the data which lead me to...
  4. L

    Interpreting scaling vs centring vs normalizing negative binomial model

    Hello, I'm a bit confused between the difference between scaling and centring in a negative binomial regression. My model looks like this: invertebrate abundance= Year +shoot count + epiphyte biomass(g) + epiphyte bio*shoot count Years: 2015, 2016 Shoot count range:1-30 Epiphyte bio...
  5. L

    Interaction term with no biological significance

    Hello friends, I've used a negative binomial GLM to look at how invertebrate abundance (over dispersed) is affected by seagrass density. There is a negative interaction between seagrass density and epiphyte biomass (the little plants growing on seagrass blades that invertebrates eat)...
  6. S

    Interpretation help for my negative binomial regression --> Testing for curviliniarit

    Hello everyone, I am a newby to that forum, so I hope my question is not redundant. I am currently sitting on my master thesis where I investigate which effect diversity in teams has on publications. Herefore, I have a dependent variable 'publications' which is a count variable. I have two...
  7. kiton

    (Poisson/NegBin, RE) Estimation of time-invariant predictors in a panel model

    Hello dear forum members, For a time being I had been working with the following model (Stata command format): - xtpoisson y x1 x2 x3 x4 x5, fe- where, y(it) is a count DV, x1-x2(it) are controls, and x3-x5(it) are the predictors of interest, i -- denotes an individual (N = 1750), and t...
  8. L

    Report insignificant results negative binomial

    Hello everyone, I've used a negative binomial model to predict invertebrate densities. The model fits but is not significant, so I don't want to waste space with a graph in my final report. I want to make simple table showing the coefficients and p values. Does anyone have an example...
  9. kiton

    Addressing omitted variable bias in count panel model

    Hello dear forum members, My study aims to address the question about physician ratings: Do they have an impact on the business value (as proxied with new patient referrals)? The sample is a panel of of U.S. oncologists (N=1,694) observed from 2009 to 2013. The outcome is a count, so for the...
  10. F

    Process capability - Negative Binomial

    Dear All, I have attribute that show overdispersion and seem to be distributed according to a negative binomial distribution. I have the following questions: 1. How can I check in Minitab if my data is distributed according to Negative Binomial? (I used Crystal Ball for this specific...
  11. L

    Can I use a Negative Binomial Regression for a Continuous Outcome?

    Hello, My outcome is Sugar intake with a highly skewed continuous outcome variable. The histogram and variable details are Attached. Since the distribution is highly skewed and has a very high variance (12.78) compared to the mean (2.67) I thought I could round each decimal to the nearest...
  12. S

    In a negative binomial GLM or GLMM what does theta stand for?

    When using a GLM or GLMM with a negative binomial distribution in R it is usually necessary to set the value of theta in the model. But what does theta actually stand for? And how do I caluclate it? I have been able to get around this for now by setting my models to calculate theta for me...
  13. D

    Negative Binomial Regression in R

    Hi all, I am fairly new to the R world. I need some help with correct syntax for running a negative binomial regression/zero-inflation negative binomial regression on some data. I am trying to run a regression that looks at how race/ethnicity influences the number of summer meal sites in a...
  14. B

    beginner's specification problems

    Hi, I am doing an assignment on unemployment (DV) and racial discrimination - specifically african-american population - and I am in doubt whether to use percent of resident population black resident alone, or black alone resident population. If I use the latter, would I need to switch from an...
  15. T

    Negative Binomial Distribution? NEED ADVICE AND HELP!!!!

    Assume City A has three parties, Party B, Party C, and Party D, with n1, n2, n2 citizens in them, respectively. Assume, for people in B, they will always support the motion by the government, while, for people in C, they will always be against the government. However, those in D will support the...
  16. C

    Plotting the pdf of a negative binomial distribution using mean and stnd deviation

    I have been using a negative binomial distribution to describe my data; in order to allow me to randomly sample from the parameterised distributions. I have had no problems getting r (the number of successes) and p (the probability of success) for my distribution. My problem is that I would like...
  17. S

    Comparing negative binomial model to the null model with offsets

    Hi there, I have a negative binomial model of count data with an offset (total counting effort) in R: L1<-glm.nb(counts~offset(log(total.counts))+temperature, link='log', data=dat) and I want to compare it to the null model. Am I right in thinking I can just do...
  18. L

    negative binomial regression coefficients and exp(b)

    Thank you so much anyone... I have the results of a negative binomial where the DV is the log count of meals obtained. I have continuous predictors and I have my DV back logged, i.e., exp(b) with CIs for easier interpretation in my paper. The thing is... I am not easily interpreting my exp(b)...
  19. E

    Interaction and negative binomial regression analysis for criminological thesis

    Hello, For my master's thesis I'm conducting a research on the influence of morality and self-control on self-reported delinquency. Morality is a metric scale, while self-control is divided into three subscales, being temper, impulsivity and risk-taking behaviour, which are all metric scales...
  20. S

    Estimating failure rate

    Hi all, I need some assistance in guiding folks on a sampling problem. We have an application that performs transactions and we're in the process of making modifications. We can't (unwilling to spend the money) test all the possible permutations of all the variables, so we want to randomly...