Skip to main content

Questions tagged [odds]

The odds of an event is the ratio of the probability that the event will happen (p) to the probability that it will not happen (1-p).

Filter by
Sorted by
Tagged with
1 vote
1 answer
35 views

Interpretation of average marginal effect logistic regression model [duplicate]

I am currently writing a master thesis on the relationship between the unemployment rate (measured in percentage points) and first birth hazards (i.e. the probability of having a first child) using ...
Flap's user avatar
  • 13
1 vote
0 answers
27 views

logit model - labor probability(odds ratio) [duplicate]

The logit model is given: $$ \text{Labor probability} = \alpha + \beta_1 \cdot \text{income} + \beta_2 \cdot \text{age} + \beta_3 \cdot \text{education} + \beta_4 \cdot \text{young kids} + \beta_5 \...
silvia's user avatar
  • 11
1 vote
0 answers
19 views

Why is the ordinal logit also called POLR?

The ordinal logit is often referred to as proportional odds logistic regression (POLR, e.g. in R). I am wondering where the term proportional is coming from? It is clear to me that the logit model is ...
Marlon Brando's user avatar
0 votes
0 answers
7 views

Relative odds between different unrelated events

I would like to know the method by which to calculate the following… Based on the provided data, what are the odds of each of these events being highest when they next occur a month from now, and what ...
Greg Kozak's user avatar
6 votes
2 answers
443 views

How should I interpret categorical with continuous variables in a logistic regression output?

I am trying to interpret the output of a logistic regression with categorical and continuous variables. I am a bit struggling to get the concept of "other values fixed / other variables constant&...
Gustav's user avatar
  • 127
10 votes
2 answers
617 views

Why is E(θ / (1 - θ)) different than E(θ) / (1 - E(θ))?

I've encountered a problem question: The probability of success for a random variable follows a Beta(5, 3) distribution. The posterior mean is θ = 0.625. The odds of success is defined as θ / (1 - θ)....
alexandrosangeli's user avatar
1 vote
1 answer
34 views

Converting Risk Ratios to Odds Ratio in case-crossover trial for meta-analysis

I am doing a meta-analyss of case crossover & time series studies. so the problem is some studies have reported the RRs, & I need ORs. The data I have is not enough which is -Total sample size ...
Abdullah Akram's user avatar
1 vote
1 answer
42 views

Does the likelihood of getting a certain person in secret santa decrease if you were going first versus going last, and how much?

Feeling a bit stupid but here goes: There are 6 people in this secret Santa thing, one of them is person X and another is person Y. All the names are put into a hat and each person comes up to take a ...
SecretSantaQuestion's user avatar
1 vote
0 answers
71 views

Strange interpretation of odds ratio from logistic regression

I am involved in writing a manuscript applying logistic regression to estimate rates of seafood mislabelling. The model (fitted using glm() with the default logit ...
compbiostats's user avatar
  • 1,579
2 votes
2 answers
114 views

Difference between Probability and Effects in Logit Models

when I run a logistic model I get log odds that I can easily convert to probabilities. What I don't understand is how can I use percentages instead? Here's the code: ...
Luca's user avatar
  • 21
2 votes
1 answer
188 views

Algorithm to find the probability of a number given the probability of another number?

Let me preface that I'm not sure if this is even possible and I'm unsure of what math principals would apply but I'm trying to build an algorithm for a sports betting project that can find the ...
AJK's user avatar
  • 71
8 votes
4 answers
3k views

Interpretation of coin toss: odds of getting a tail in two coin flips

Let's say someone asks me: What are the odds of getting a tail when a coin is flipped twice? Assuming the coin is fair and tosses are independent, I see two ways of solving this problem: If we ...
Nick's user avatar
  • 101
0 votes
0 answers
25 views

Use of weights in a binomial model, with the response no longer a proportion

I am studying the factors that influence mosquito feeding behavior. In the experiments, N mosquitoes are exposed to a host for a duration t. At the end of this exposure, we count how many mosquitoes (...
alpagarou's user avatar
0 votes
0 answers
136 views

Convert β to odds ratio?

I would like to convert β-values into odds ratios. It is about table 1 on page 5 in the article „A revised inventory of Adverse Childhood Experiences“ https://www.semanticscholar.org/paper/A-revised-...
Daniel Germany's user avatar
3 votes
1 answer
144 views

Beta regression: slope of scaled predictor

I want to fit a beta regression with an scaled continuous predictor, and express the slope in terms of proportion (not at the transformed, log-odds scale). In other words, I would like to express the ...
M. Riera's user avatar
0 votes
1 answer
61 views

Correct interpretation of a logistic regression coefficient

I have a simple confusion regarding the interpretation of logistic regression. Suppose married people are more likely to be employed compared to single people. In here, unemployment = 0, employment = ...
Prasanna's user avatar
1 vote
0 answers
51 views

Risk ratio or odds ratio?

I have a question which may seem stupid. This is for a retrospective cohort study. I have a table like this for my outcome: Among the 20,000 patients in group A, 4671 are dead (23.55%). Among 50,000 ...
user19745561's user avatar
2 votes
1 answer
206 views

Scaling odds ratios and converting them to probability

I'm trying to calculate a scaled odds ratio and convert them into percentages for an analysis I am doing. I have just one independent variable in the model, SAT score. Dependent variable is college ...
doogie's user avatar
  • 23
0 votes
1 answer
164 views

model formulas for glmer

I have a glmer (library lme4) logit model that I conducted in R. I have very basic knowledge in stats and glmm models are completely new to me. My Models in R basically are like this: ...
Balina's user avatar
  • 5
1 vote
0 answers
23 views

Does testing the statistical significance of an odds ratio always produce a smaller p-value than a z-score obtained from the test of two proportions?

I have a question regarding the significance testing of an adjusted odds ratio vs. the significance testing of the adjusted difference between two proportions using a z-score. This is following the ...
Charlie's user avatar
  • 11
1 vote
0 answers
62 views

Calculate difference in log odds between two logistic regression models

I would like to calculate the difference in log-odds between the error of two logistic regression models, given the correct answer aka ground truth (depression present${}= 1;$ depression absent${} = 0$...
Betsy S.'s user avatar
  • 363
1 vote
0 answers
23 views

Should the odds ratio be used to judge incremental information in psychological scales?

I am looking at the incremental validity of the MMPI-A-RF (a psychological instrument) and MACI (another psychological instrument) in the prediction of the DSM code for depression disorders found in ...
Madison Smart-McCarthy's user avatar
1 vote
0 answers
15 views

Score for over/under representations of a variable in sub-group

I have a corpus of book publications split into different clusters. I have information about the nationality of the authors (variable A) and the nationality of the publishing company (variable B). In ...
Homard's user avatar
  • 11
3 votes
1 answer
105 views

Simpson's paradox detected via multivariable logistic regression?

This is not homework. This is simple self-learning from real data. I am fitting a logistic regression model as follows: $$\text{logit}(p_i) = \beta_0 + \beta_1 race_{i} + \beta_2 x_{2i} + \beta_3 x_{...
Jacob's user avatar
  • 540
2 votes
1 answer
47 views

Better odds with $9 bucks on lotto?

I think I have a juicy one! My state's lotto game is 2 dollars, you select 6 numbers between 1 and 40, (odds to get all 6 are 1 in 3,838,380). However, if you pay an extra 1 dollar (so 3 in total) you ...
Hopeful Financial Planner's user avatar
1 vote
0 answers
90 views

How to adjust team win probability based on in in game win probability

I have a formula to calculate each team's win probability based on their win rates and home court advantage. So lets say I use it to determine that team A has 45% chance to win and team B has 55% ...
glockmog's user avatar
2 votes
1 answer
47 views

Probably that an item was not selected in a sample

I have a population that a sample was taken from, and one "group" was not selected in the sample. I am wanting to find the probability of one group not being selected. I will use red/blue ...
Gregory Windeler's user avatar
1 vote
1 answer
520 views

Scale of y-axis of a plot showing the predicted outcome risk for a continious predictor in a logistic regression model

I was previously informed in another thread that my plot on the y-axis is showing odds and not odds ratios. The following example code and figure depict this. ...
Gurkenhals's user avatar
1 vote
1 answer
85 views

What are the odds for winning this drinking game?

Out of pure boredom during the corona period back in 2020 I 'invented' a drinking game which seemed to have a fair outcome, but I am not sure. We were sitting on the couch and after a lot of beer, and ...
Pim's user avatar
  • 13
1 vote
2 answers
353 views

Logistic regression coefficients compared to the mean in R

No doubt this is a stupid question but I can't seem to find help anywhere online. I want to do a logistic regression with 2 independent variables. Ideally, I would like to see how each variable ...
Leonhard Euler's user avatar
1 vote
0 answers
29 views

Probability of net gain being greater than 0 lottery question

I'm working on some practice exams and I came across a probability question that stumped me. "In a lottery game, for any lottery ticket bought at random, the chance of winning each prize is ...
carter's user avatar
  • 11
0 votes
0 answers
29 views

Card Collecting Odds

My friends and I are thinking about participating in an event to collect these cards. There are 8 total cards in the set, and we can buy a pack of 10 random cards at a discount. So we were wondering, ...
Swisse's user avatar
  • 1
2 votes
1 answer
95 views

Can we compute the expected value of a football match final score?

I am asked to make predictions for the exact final result of some football matches. To be clear, I do not have to place any bets on them, just guessing the final score. To do that I was thinking about ...
rusiano's user avatar
  • 566
0 votes
1 answer
192 views

Better to pick first or last?

If 8 balls placed in a bowl and 1 had a prize and 8 ppl are choosing in order each ball. Is it better to go first or last without putting balls back in once each person takes one out?
Diego Serrato's user avatar
3 votes
1 answer
140 views

Mean of geometric distribution is odds?

Context: I mean the $P(X=k)=(1-p)^k p$ not the $P(Y=k)=(1-p)^{k-1} p$. Apparently the mean of the 1st kind of geometric is $\frac{1-p}{p}$ instead of $\frac{1}{p}$ for the 2nd kind of geometric. I ...
BCLC's user avatar
  • 2,444
1 vote
0 answers
31 views

Getting probabilities from odds

Simple question here. Consider an urn with balls of three colors. 50 % of the balls are red, 30 % black, and the remaining balls green. The experiment is to draw a ball from the urn. What is the ...
ImNotLost's user avatar
4 votes
1 answer
47 views

Numerically stable log-odds of intersection of independent events

Suppose we have independent events $E_1,\dots,E_n$, and define $E = E_1 \land \cdots \land E_n$ to be the conjunction (logical-and) of these events. Let $p_i=\Pr[E_i]$, $p=\Pr[E]$. If we are given ...
D.W.'s user avatar
  • 6,688
0 votes
1 answer
105 views

How can I calculate the odds of exposure for >1 outcome group, combined, using the rms::lrm function. Predict? Contrast?

I have been using a logistic model from rms::lrm to estimate the odds ratio of a binary exposure on an outcome, using splines [time] as Frank Harrell recommended. I ...
josh's user avatar
  • 1
1 vote
1 answer
652 views

Probability of Winning a Prize from a raffle with Multiple Winners with Multiple Entries

So let's say there's a raffle to win 500 prizes for a raffle and you can have multiple entries. There are currently 200,000 entries and I have 200 of those entries. Each person can only win once as in ...
rsspitt's user avatar
  • 11
3 votes
1 answer
428 views

What is the effect size `h` in `pwr::pwr.p.test` in `R`?

The R package pwr has a function for calculating the required sample size for a one-sample proportion test (I assume a z-test ...
Dave's user avatar
  • 65.1k
2 votes
1 answer
36 views

odds ratio for two variants of covid [duplicate]

I need to calculate the odds ratio for mechanical ventilation and death in relation to different early COVID-19 symptoms for two COVID variants - delta and omicron. How should I do it? I want to ...
COV's user avatar
  • 21
5 votes
1 answer
193 views

What is the intuition behind the odds scale?

What is an intuitive explanation of the odds scale? In a logistic regression such as $$logit(p) = \beta_0 + \beta_1 x$$ we often interpret $\beta_1$ by looking at the odds ratio, $e^{\beta_1}$, which ...
thomaskeefe's user avatar
2 votes
2 answers
3k views

Interpretation of continuous variable in an odds ratio for logistic regression

I have an odds ratio of 1.02 for x variable (Age, a continuous variable measured in units "1 year"). My response variable is Y. I would interpret this as for every increase in Age by 1 year ...
Harcluna's user avatar
1 vote
1 answer
137 views

Log of the odds in Logistic Regression

In simple logistic regression i noticed that many researcher neglect the constant part of the logistic regression equation. Log(odds) = a + b Gender (say that 0 = Female and 1 = Male) So the log of ...
Hussain's user avatar
  • 151
3 votes
0 answers
249 views

Intuition of the log odds linearity assumption for logistic regression

I'm currently having trouble understanding the assumption of logistic regression that the input variables must be linearly related to the log odds. Specifically, what actually happens to the model ...
Ryan's user avatar
  • 31
1 vote
1 answer
199 views

D&D Probability question: why am I wrong?

In Dungeons and Dragons, the primary die used for success or failure is the D20, or 20 sided die. A 1 is a critical failure, and a 20 is a critical success. When one has advantage, one rolls 2 dice ...
Isaac's user avatar
  • 113
4 votes
2 answers
3k views

Interpretation of Odds Ratio (OR) in Fisher's exact test

I've tried using R operating Fisher's exact test to test for independence of the 2 datasets below and struggling to interpret the Fisher report. Please have a look at the data and the Fisher's test ...
JaFranke's user avatar
2 votes
1 answer
2k views

Probability your name will be drawn out of a hat without replacement

Let's say you put your name in a hat with 7 other names (n=8). Only 4 names will be drawn from said hat. Each name will be drawn one at a time, without replacement. What is the probability that your ...
Tommy's user avatar
  • 23
7 votes
3 answers
2k views

Flipping Coins : Probability of Sequences vs Probability of Individuals

Here is a problem I thought of: Suppose I am watching someone flip a fair coin. Each flip is completely independent from the previous flip. I watch this person flip 3 consecutive heads. I interrupt ...
stats_noob's user avatar
0 votes
0 answers
55 views

Chances of four people being drawn together

There are eight people in a golf group. There is going to be a draw to split them into two groups of four. There are four people within the group who would like to be drawn together. What are the odds ...
Mick Mousey's user avatar

1
2 3 4 5