1. T

    Non-parametric tests that do not assume equality of variance

    Hi all, i have a Before-After-Control-Treatment (2x2) design, resulting in two independent groups of scale data (samples in two water streams, in one a treatment has been installed at some point, both streams (two physical different locations) were sampled before and after at various occasions)...
  2. M

    Sensitivity of a diagnostic test

    There is an exercise that I am not able to solve: Diagnostic tests A1 and A2 are used to detect the presence or absence of a disease. The results of A1 and A2 are a priori independent of the presence or absence of the disease. A1 and A2 have sensitivity Sen1 and Sen2, respectively. A new...
  3. P

    Comparing sensitivity, specificity, accuracy between two different diagnostic tests used on the same group of patients

    Dear all Could someone advice on how I should go about comparing the sensitivity, specificity, accuracy between two different diagnostic tests used on the same group of patients on SPSS? ie: sensitivity (test 1, test 2, p-value) specificity (test 1, test 2, p-value) accuracy (test 1, test 2...
  4. J

    Adapted version of sensitivity / specificity for disease detection

    I have data collected from sensors to detect disease in several individuals. Each individual has a known disease status (labeled Actual in the table below) for each day and a predicted disease status (Predicted in the table below) from prediction equations performed on the sensor data. I am...
  5. V

    Logistic Regression model: a significant predicting variable with low sensitivity?

    Hi fellow forum members! Thank you in advance for your time! I used binary logistics regression (SPSS) to determine the relationship between ambient noise levels (a continuous variable on a logarithmic scale, dB) and a single dichotomous dependent variable ("yes" - 1- for whale positive...
  6. E

    Calculating Sensitivity and Specificity of Combined Testing...With a Surprise.

    Ok guys. I have an interesting question. I'm a biomedical engineering student from Georgia Tech and for one of my classes I have to implement screening policy for liver cancer. I decided to implement combined testing. It looks like this Test A High risk factor -...
  7. rogojel

    Bayes statistics - sensitivity to priors

    Hi, I came across a statement in a review of a research field, where they were determining an unknown parameter using Bayesian statistics. The reviewer said that using Bayes statistics to estimate the parameter is uncontroversial, but many of the papers dealing with this estimation are weak...
  8. F

    Sensitivity/Specificity: determining confidence intervals for a small sample size

    I'm conducting a study to determine the validity of a diagnostic test, by comparing its results to a reference standard. The variables I'm dealing with are all categorical. Sadly, I couldn't obtain a proper sample size since the prevalence of the disease is very low (about 6%). When I...
  9. A

    Classification for cloglog

    Howdy! I need to know how one can go about obtaining the overall classification, the sensitivity and specificity of a cloglog estimation in Stata. Is there an equivalent to that beautiful estat classification command that works so well in logits and probits? Many thanks!
  10. A

    Interpreting sensitivity and specificity with corresponding PPV and NPV

    Hello, I have calculated sensitivities, specificities with pos and neg predictive values for different cutoff values of two biomarkers. What i get is the following: Biomarker 1: High spec (92%) low sens (20%) with high NPV (91%) and low PPV (22%) Biomarker 2: High sens (90%) low spec...
  11. S

    WANTED: statistical basis for subtest weighting

    Hello everyone, I am planning my Master thesis project in Neuropsychology and I am currently facing a statistical/mathematical challenge. Here is what it is about: Three patient groups will be administered a cognitive screenind instrument with seven subtests. Originally, the scores...
  12. M

    calculate sample size for sensitivity and specificity in a new diagnositic test

    My question is difficult to me, I had read an article about how to calculate sample size the foot note tole me"" ε = required absolute precision on either side of the sensitivity "" what is the absolute precision means ? and generally how to chose required absolute precision on either...
  13. S

    Sensitivity and Specificity and explained variance.

    Hi. I have one dependent variable (Y) which is binary. I have this data for 100 subjects. I want to generate binary data for 3 independent variables (X1, X2, X3) (so effectively I want to generate 3 columns of data with 100 values in each column) I want to generate this data according to...