Can odds ratio be more than 100?

A result greater than 100 represents greater odds of an outcome when exposed to a treatment. Conversely, an OR less than 1 indicates less odds of an outcome when exposed to the treatment.

How high can an odds ratio be?

As odds of an event are always positive, the odds ratio is always positive and ranges from zero to very large. The relative risk is a ratio of probabilities of the event occurring in all exposed individuals versus the event occurring in all non-exposed individuals.

What is an extremely high odds ratio?

An odds ratio greater than 1 indicates that the condition or event is more likely to occur in the first group. And an odds ratio less than 1 indicates that the condition or event is less likely to occur in the first group. The odds ratio must be nonnegative if it is defined.

Can an odds ratio be above 1?

The magnitude of the odds ratio is called the “strength of the association.” The further away an odds ratio is from 1.0, the more likely it is that the relationship between the exposure and the disease is causal. For example, an odds ratio of 1.2 is above 1.0, but is not a strong association.

Can odds ratio be infinite?

Odds = probability / (1 - probability) therefore odds can take on any value between 0 and infinity whereas probability may vary only between 0 and 1. Odds and log odds are therefore better suited than probability to some types of calculation.

Relative Risk & Odds Ratios

What does infinite odds ratio mean?

The odds ratio is asymmetrical and can range from 0 to infinity; the odds ratio cannot be negative. Odds ratios between 0 and 0.99 indicate a lower risk, between 1 and infinity indicate a higher risk, and equal to 1 indicate no relationship between two variables.

What is the odds ratio paradox?

The odds ratio paradox relates to three chained proportions com- pared between the same two groups, and involves the magnitude, but not the direction of the effect.

What is the cutoff for odds ratio?

If a predictor is a risk factor then the 95% CI of the odds ratio needs to be greater than 1 and if it is found not to be a risk factor then the 95% CI of the odds ratio needs to be less than 1.

What does an odds ratio of 0.8 mean?

Examples. RR of 0.8 means an RRR of 20% (meaning a 20% reduction in the relative risk of the specified outcome in the treatment group compared with the control group).

Do odds have to be between 0 and 1?

Logistic Regression Uses Odds

A probability must lie between 0 and 1 (you cannot have more than a 100% chance of something). Odds are not so constrained. Odds can take any positive value (e.g. a ⅔ probability is the same as odds of 2/1).

What if odds ratio is greater than 1?

Odds Ratio

If the OR is <1, odds are decreased for an outcome; OR >1 means the odds are increased for a given outcome.

What is 75 odds ratio?

Thus, an odds ratio of . 75 translates into a failure rate of 15.8% in the treatment group relative to an assumed failure rate of 20% in the control group. This translation of odds ratios into an easily understand metric is commonly used in meta-analyses of odds ratios.

What does an odds ratio greater than 1 mean?

Important points about Odds ratio:

OR >1 indicates increased occurrence of an event. OR <1 indicates decreased occurrence of an event (protective exposure) Look at CI and P-value for statistical significance of value (Learn more about p values and confidence intervals here)

Why is odds ratio exaggerated?

The odds ratio will always overstate the case when interpreted as a relative risk, and the degree of overstatement will increase as both the initial risk increases and the size of any treatment effect increases.

Are odds ratios ever negative?

The odds ratio is always positive, although the estimated log odds can be positive or negative (log odds of −0.2 equals odds ratio of 0.82 = exp(−0.2)).

What does an odds ratio of 0.70 mean?

In the study by Lin et al, the probability of the event was 59% and, using the calculation proposed by Davis et al,² we can estimate that the odds ratio of 0.70 is equivalent to a relative risk of 0.85—that is, the odds ratio is 18% smaller than the relative risk.

What does an odds ratio of 1.5 mean?

It means that the odds of a case having had exposure #1 are 1.5 times the odds of its having the baseline exposure. This is not the same as being 1.5 times as probable: odds are not the same as probability (odds of 2:1 against means a probability of 13).

What does an odds ratio of .98 mean?

The reported odd ratio of 0.98 at less than 1 indicates that for every additional parameter of the tested independent variable, they were . 98 times likely to report the likelihood of the test question.

How do you interpret odd ratio in logistic regression?

The interpretation of the odds ratio depends on whether the predictor is categorical or continuous. Odds ratios that are greater than 1 indicate that the event is more likely to occur as the predictor increases. Odds ratios that are less than 1 indicate that the event is less likely to occur as the predictor increases.

What is the odds ratio for dummies?

What is an odds ratio? An odds ratio (OR) is a measure of association between an exposure and an outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure.

What is the difference between likelihood ratio and odds ratio?

The odds ratio is the effect of going from “knowing the test negative” to “knowing it's positive” whereas the likelihood ratio + is the effect of going from an unknown state to knowing the test is +. “Unknown state” is not always well defined so I stick to logistic regression for the diagnostic problem.

When can odds ratios mislead?

Substantial discrepancies between the odds ratio and the relative risk are seen only when the effect sizes are large and the initial risk is high.

What is the assumption of odds ratio?

The proportional odds assumption means that for each term included in the model, the 'slope' estimate between each pair of outcomes across two response levels are assumed to be the same regardless of which partition we consider.

What is the odds ratio Bayes rule?

Fortunately, Bayes' theorem has a very intuitive formulation, not in terms of probabilities but in terms of odds ratios. The odds ratio for a probability p is p / (1 – p); if p = 9/10, then it has odds ratio 9/10 / 1/10 = 9.

Can odds ratio be 30?

Maybe it was a combination of low power and selection by significance that rendered so large an effect? With right-hand tapping, the odds ratio is 8/4/(7/4) = 1.1 (no framing effect). With left-hand tapping, it is 12/1/(3/9) = 36. So the ratio of odds ratios is about 30.