Refers to a measure of association between two binary variables. If $X,Y$ are binary outcomes and $p_{ij} = P(X=i,Y=j)$, the odds ratio is equal to $$ {\rm OR} = \frac{ p_{11} p_{00} }{ p_{10} p_{01} } $$ When ${\rm OR} 1$ indicates a positive relationship. More info is available at ...
0
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0answers
18 views
Exact version of Bowker's test?
I know there is an exact version of McNemar's test for symmetry, and am just wondering if there is an exact version for Bowker's test. From my understanding the exact version of McNemar's test uses ...
0
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0answers
63 views
Regression with a ordinal scale dependent variable in the context of panel data
In my panel data I observe a quite large amount of different individuals for a fixed time duration. The time axis is fixed for every individual, i.e., I observe 20 time points for every individual.
...
0
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0answers
63 views
1
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1answer
88 views
Why is the CI for an odds ratio not always centered on the sample value?
Also, what will tend to produce a CI in which the sample value is far above the center, or far below the center?
2
votes
2answers
97 views
How to compare whether the odds of success of different levels of a predictor are different from 0
I hope I am able to word my question clearly. Suppose I have a model below:
glmer(Y~X + (1|subject), family="binomial", data=dat)
The intercept is the log odds ...
0
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2answers
142 views
Logistic regression and odds ratio
If the odds ratio is greater than one with an insignificant p value for a variable in logistic regression should the variable be kept in the model?
Can I select the variable with odds close to 1?
...
1
vote
1answer
210 views
Calculate combined odds ratio between two factors
I am using synergy factors to test synergy between two variables. The equation is simple enough, where $OR_{12}$ is the combined odds ratio for variables 1 and 2:
$ SF = \dfrac{OR_{12}}{(OR_1 \times ...
0
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0answers
67 views
Comparison of hazard ratios
I have study population with 900 patients, of whom 200 have had an adverse outcome. This outcome can be divided into two distinct entities.
I would be interested to study whether risk factor for ...
2
votes
2answers
76 views
“Exposure” and “Outcome” can be switched without changing the odds ratio?
I'm enrolled in an introductory course in statistics. In one of my lecture notes, the instructor explains why Odds Ratio is popular and he mentions:
"Exposure" and "Outcome" can be switched without ...
1
vote
1answer
130 views
Descriptive measures for 2x2 crosstabs with zeros
For 2x2 contingency tables I already know the RR (Relative Risk) and the OR (Odds Ratio). However none of these two is good dealing with empty cells in the table.
| A | -A |
B | n11 | n12 ...
0
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1answer
192 views
How to calculate 95% CI for OR for a different reference category without running the SAS logistics again?
My question is about calculation of confidence interval (CI) for odds ratio (OR) from a SAS output of a logistic regression model for a different reference category without running the SAS program ...
0
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0answers
29 views
Would it be appropriate to calculate the odds ratio while comparing difference in risk factors for a given disease between two genders
I recorded risk factors for a given disease and then compared them between the two genders. I have calculated the p value as well to assess the statistical significance. In the current scenario, would ...
3
votes
1answer
212 views
Hypothesis test for odds ratios
I have two possible exposure variables (A and B) for use in a statistical model predicting a binary health outcome. I have fitted models with each variable separately and now know that one variable ...
3
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1answer
573 views
Negative coefficient in ordered logistic regression
Suppose we have the ordinal response $y:\{Bad,Neutral,Good\} \rightarrow \{1,2,3\}$ and a set of variables $X:=[x_1,x_2,x_3]$ that we think will explain $y$. We then do an ordered logistic regression ...
-1
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1answer
113 views
Clinical trial question Confidence Interval
Data are collected in a clinical trial evaluating a new compound designed to improve wound healing in patients. The new compound is compared against a placebo. After treatment for 5 days with the new ...
7
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2answers
1k views
Exponentiated logistic regression coefficient different than odds ratio
As I understand it, the exponentiated beta value from a logistic regression is the odds ratio of that variable for the dependent variable of interest. However, the value does not match the manually ...
4
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3answers
402 views
More interpretable measure of association than odds ratios for contingency tables with 0 counts
How strong/weak of a correlation is this?
...
4
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1answer
594 views
Interpretation of simple predictions to odds ratios in logistic regression
I'm somewhat new to using logistic regression, and a bit confused by a discrepancy between my interpretations of the following values which I thought would be the same:
exponentiated beta values
...
2
votes
3answers
468 views
Interpreting odds ratios
I have the following set of results for one of the factors (birth weight) with different levels and their corresponding Odds ratios for survival. I am using the first level (<1.25) as the reference ...
0
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1answer
507 views
Calculating a pooled odds ratio from an adjusted odds ratio?
I have individual adjusted odds ratios from different articles, and I want to combine them to calculate a pooled odds ratio, e.g., aOR 2.13(1.43-3.18) and ...
1
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2answers
490 views
Converting OR to percentages and interpretation
We have been given the following for home work and I have calculated the OR however I am confused with the next 3 questions on percentages. Can someone help and explain and also what is the ...
0
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0answers
99 views
Meta-analysis using GWAS datasets of different diseases
It is well known that in Meta-analysis of Genome-wide association studies (GWAS) we combine the results of independent studies to get a pooled effect estimates (Odd ratios or betas) in order to ...
3
votes
1answer
593 views
Odds ratio and confidence interval in meta-analysis
I need to calculate the pooled odds ratio and associated 95% confidence interval for meta-analysis of 2 studies about the risk of bleeding. The only information I have is the odds ratios and 95% ...
2
votes
1answer
166 views
Is it appropriate to calculate odds ratios between groups matched on covariates (propensity scores)?
I have a data set that includes a primary dichotomous independent variable (e.g., smoking), a primary dichotomous dependent variable (e.g., chronic back pain), and several covariates (e.g., diagnosis ...
0
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1answer
762 views
How to calculate probabilities for a 4 by 2 table?
I have collected data about test subjects which are classified into 4 categories, and I want to calculate the probabilities (odds ratios?) of developing some condition for a test subject in one ...
1
vote
1answer
245 views
What is the effect size for the interaction of a 2X2X2 contingency table?
I am computing the interaction in several 2X2X2 tables (i.e. in each case, I have eight frequencies), see for an example this file.
I have two predictors (low vs high 'threat' and low vs high ...
0
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1answer
5k views
How to get odds ratio in a table in SPSS?
I have survey data from students from two Universities. One of the questions in the survey had 4 response categories and students were allowed to check only one (categorical variable).
I want to make ...
3
votes
1answer
234 views
Combined odds ratio
I wonder if there's a way to calculate the combined odds ratio for certain SNPs in a meta-analysis of a several GWAS, even when you don't have the SE, neither beta, for each individual study?
Thank ...
0
votes
1answer
162 views
Please help to understand Agresti's book
I need some help to understand some topics in Agresti's Categorical Data Analysis. In section 6.3.1 (p 231), he provided a model like:
$$
\text{logit}(\pi_{ik})=\alpha+\beta x_i+\beta_k^Z
$$
where ...
3
votes
2answers
554 views
Comparing odds ratios of continuous and discrete variables
I need to compare the ability of two methods to predict an event with a binary response. Each method produces a score, where the higher score indicates 1 and a lower score indicates 0. I am looking to ...
0
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2answers
593 views
Adjusting data for age and bmi
I am doing a study on the effects of bad blood sugar control on patients. BMI, age, type of diabetes (Type 1 and 2 or gestational diabetes) are all variables. Outcomes include C section, early labour ...
1
vote
1answer
479 views
Interaction terms interpretation
How do you interpret an odds ratio of an interaction between two continuous variables $x_1, x_2$? Would you fix $x_2$ and let $x_1 = x$ and $x_1 = x+1$?
0
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1answer
773 views
Odds ratio for continuous variable
I have a question
How would you interpret the odds ratios for a continuous variable?
2
votes
1answer
2k views
How to calculate odds ratio and p-values for Fisher's test?
I'm trying to perform Fisher's exact test in R. Im calculating odds ratio like this
$$\frac{(\text{no. of successes in my set}) \cdot (\text{no. of failures in background set})}{\text{(no. of ...
0
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0answers
205 views
Odds Ratio Between Overlapping Groups
Is it inappropriate to use odds ratio for groups that are subset of each other? For example, comparing GPA of female students to GPA of all the students. (This is just an example, not what I am really ...
2
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0answers
1k views
The effect of skewed continuous predictors in a binary logistic regression model
I am analyzing data with a binary outcome and a variety of continuous and categorical (including dichotomous) predictor variables. My approach is to perform a binary logistic regression and to treat ...
12
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1answer
2k views
Poisson regression to estimate relative risk for binary outcomes
Brief Summary
Why is it more common for logistic regression (with odds ratios) to be used in cohort studies with binary outcomes, as opposed to poisson regression (with relative risks)?
Background
...
1
vote
2answers
102 views
Can odds ratios increase if you include more variables?
Suppose one wants to compute the odds ratio of a disease for a person in group $A$ versus that of a person in group $B$. Suppose we consider the following: (i) include age in the odds ratio ...
1
vote
1answer
189 views
Odds ratios question
If you have a categorical variable with $k$ levels (so $k-1$ indicator variables), is there an easy way to calculate the odds ratio? Suppose the first level is the reference level. The model would be ...
5
votes
1answer
778 views
How to conduct a meta-analysis on studies that report results variously as odds ratios, hazards ratios, or rate ratios?
I'm doing a meta-analysis of some studies that report results variously as odds ratios, hazards ratios or rate ratios (all with confidence intervals). Is there any way to combine these ...
4
votes
1answer
205 views
Generating data with a pre-specified odds ratio
I have to simulate (in javascript) the likelihood that members of a certain population would have a disease, given a contextual value. All information I have comes from papers that show odds ratios ...
3
votes
0answers
259 views
What is the best statistical method to compare case fatality rates of 17 years for 2 different states?
I have Case Fatality Rates (deaths per 100 cases) for 2 different states receiving different treatments for 17 years.
What is the best statistical method to compare Case Fatality Rates ?
The data ...
1
vote
1answer
353 views
Odds ratios multiple comparisons
I have to assess for each product p, the odds ratio associated (success/failure). The data are in this table:
...
5
votes
3answers
4k views
How to calculate confidence intervals for pooled odd ratios in meta-analysis?
I have two datasets from genome-wide association studies. The only information available are the odd ratios and their confidence intervals (95%) for each genotyped SNP.
My want to generate a forest ...
7
votes
3answers
7k views
Logistic Regression in R (Odds Ratio)
I'm trying to undertake a logistic regression analysis in R. I have attended courses covering this material using STATA. I am finding it very difficult to replicate ...
3
votes
3answers
342 views
How to assess effect of intervention in one state versus another using annual death rate data?
I am a beginner in statistics. I have these unpublished data (cases and deaths) of a disease for 7 years (2004-2010) from 2 neighbouring states. The study was started in 2004. State 1 and State 2 ...
3
votes
1answer
578 views
What does “case-control” and “cross-sectional” mean in the context of logistic modeling?
While studying logistic modeling, I read the following statement
The fact that only odds ratios, not individual risks, can be estimated from logistic
modeling in case-control or ...
5
votes
1answer
418 views
Probability calculation, system uptime, likelihood of occurence
(redirected here from mathoverflow.net)
Hello,
At work I was asked the probability of a user hitting an outage on the website. I have some following metrics. Total system downtime = 500,000 seconds ...
6
votes
3answers
440 views
Meta analysis on studies with 0-frequency cells
I am familiar with meta analysis and meta regression techniques (using the R package metafor from Viechtbauer), but I recently stumbled on a problem I can't easily ...
3
votes
1answer
2k views
Relation between logistic regression coefficient and odds ratio in JMP
From the output of a logistic regression in JMP, I read about two binary variables:
Var1 estimate -0.1007384
Var2 estimate 0.21528927
and then
...
