1. Francisco Sáez

    Mean Squared Error explained in a visual manner (method case)

    Dear all. I would like to share with you the video I have develop in which people can understand the concepts of Bias and Efficiency of an estimator from a total practical point of view and using a simulated case (method case). If you want understand this concepts, above all for people who don't...
  2. S


    If bias (B) in terms of σ is 1.5 (i.e B/σ=1.5) find the total error. How to solve this??
  3. C

    Conjoint analysis: bias due to no-choice option and linear attribute

    At the moment I am analysing survey data using Bayesian estimation in R (bayesm package) For my analysis, I have included a no-choice option (NoneOpt) that is coded as a series of zeros. However, I also have a price attribute (Delivery.costs). What I actually want to do is keep the price...
  4. B

    Aggregate precision of a measurement instrument based on a sample of measurements whose true errors are known

    I want to estimate the accuracy and precision of aggregate data from an instrument that measures a variable that fluctuates over time by comparing a sample of its measurements to concurrent measurements made by a reference instrument. For this purpose, assume that the reference instrument...
  5. D

    survey data collected based on simple random sampling, which mainly came from the eas

    Dear Stata forum friends, I just launched one survey in the US and collected 600+ individual responses. I distributed the online survey to US citizens via Qualtrics, an online survey platform. The distribution approach is simple random sampling. I visualized the geological locations of all...
  6. U

    Checking significance of bias.

    In a new design, estimator seems to be biased but efficient than the existing design. Now I want to check whether the bias of the estimator based on new design is significant. The formula of the variance of the estimator based on new design is intractable. How can I check the...
  7. A

    Help with unbiased estimators

    I'm working on a homework problem and the question I'm stuck on is as follows: "Give an unbiased estimator for 2µ+3σ^2" I'm not sure how I would go about doing that since the mean and the variance make up the function.
  8. 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)...
  9. E

    Reduce Common Method Bias

    Hi Folks, I have a question regarding my research. I am looking into the behavior/personality of CEO on the firms general Behavior. My theory in short, a risk loving CEO will make the firm more innovative. In my dataset I have responses from both CEO and General Manager of each company...
  10. P

    URGENT: What are the statistical limits and biases in this scientific article?

    I need to deliver this exercise in the next 10 hours. QUESTION: What are the statistical limits and biases in this scientific article, which challenge its validity? THE ARTICLE: Efficacy of hepatitis A vaccine in prevention of secondary hepatitis A infection: a randomised trial Abstract...
  11. P

    Test to identify bias in staff recording data - some guidence please

    Hi, First post on this forum. Have tried to search for the correct answer in this forum, but have not found it (perhaps I'm not searching correctly) I am involved in a project where staff observe items and record their observations on an input device (iPads in this case). The data set is quite...
  12. C

    Calculating Overall Relative Bias

    I am in some trouble to understand how is to calculate the overall relative bias. In this link, there are results of overall relative bias in "Parameter estimates" sub-section under "Results" section. There they mentioned that : Could you please explain me how did they calculate it? I had...
  13. A

    Relative and absolute bias - Likert-type data

    I'm working on a data set which was collected through a questionnaire by a certain regulatory institution. 50 institutions (whole population of that type of institutions) answered a series of questions (100 questions). The answers were collected via a Likert-type form (5-items, anchored). The...
  14. A

    Spatial Econometrics - Bias?

    Dear all, I seem to be lost with the following problem in spatial econometrics: Assume the true model is a spatial error model (SEM). It is well known that using OLS for estimation is inefficient but still unbiased. Now, when I compare my OLS vs. SEM estimates in R, say, they are quite...
  15. M

    Sampling Q - why can't we replace non-responders by randomly selecting new ones?

    We are planning a survey of schools to get state estimates of substance use among youth. We are doing a two-stage survey, where the first stage is a PPS random selection of schools, and the second stage is random selection of classrooms (then the students in the classroom are surveyed). We...
  16. J

    Judging bias in assessment system with multiple assessors & scoring criteria

    I work for a grant giving charity and we use external assessors to help in our selection process. There are 30 applications for review. We have 6 assessors who will look at no more than 15 app forms each. They have to score each app out of 5 across several criteria. We total the scores and...
  17. L

    [ self-selection - nonresponse bias] 65% of population answered survey

    Dear TalkStatstters, I want to investigate possible wage gaps between different groups of people with doctorate degree, in my region. So, I have in mind a regression where the dependent variable is the log of the ratio between two average wages. I have administrative data from the whole...
  18. L

    Unbiased estimate of cross-product for unbiased vector

    Let g be an unbiased estimate of a vector G. Can g be used to find an unbiased estimate of the cross product GG′ (where G' is the transpose of G)? I'm stuck because naively using gg′ is a biased estimator, with the (upwards) bias depending on the noise in g.
  19. D

    Omitted-variable bias in the constant of multiple regression under heteroskedasticity

    Good morning, I would like to have some deeper information about omitted-variable bias. Here is the real model: Callback = Constant + b1*Race + b2*Quality + b3*Race*Quality where Race and Quality are dummies variables and Callback is a rate (between 0 and 1) If I regress this simple linear...
  20. A

    Is it possible to Reduce/Correct Bias through EM algorithm?

    I am dealing with few overdispersed count models and using mixed Poisson distributions to deal with overdispsered data. I've used MLE technique to estimate the paramters, however ML estimates are lower biased. I am trying to correct the bias using advanced technquies. I have started to read...