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What is an Odds Ratio? An odds ratio (OR) calculates the relationship between a variable and the likelihood of an event occurring. A common interpretation for odds ratios is identifying risk factors by assessing the relationship between exposure to a risk factor and a medical outcome.
What is the Odds Ratio? How to Calculate the Odds Ratio; What do the Results mean? Population Averaged vs. Subject Specific Odds Ratio; Watch the video for an overview of the odds ratio and a couple examples of calculations, or read on below:
The F-ratio, in its various forms, can be used to compare whether the variances of two samples are equal (an assumption of several statistical tests), but it finds a much broader application in the context of analysis of variance (ANOVA) to analyze factorial experiments and in least-squares regression analysis (Rice, 1988).
The F statistic is a ratio (a fraction). There are two sets of degrees of freedom: one for the numerator and one for the denominator. For example, if F follows an F distribution and the number of degrees of freedom for the numerator is 4, and the number of degrees of freedom for the denominator is 10, then F ~ F 4,10.
The values of the F distribution are squares of the corresponding values of the t -distribution. One-Way ANOVA expands the t -test for comparing more than two groups. The scope of that derivation is beyond the level of this course. To calculate the F ratio, two estimates of the variance are made.
To calculate the F ratio, two estimates of the variance are made. Variance between samples : An estimate of σ 2 that is the variance of the sample means multiplied by n (when the sample sizes are the same.).
To calculate the F ratio, two estimates of the variance are made. Variance between samples: An estimate of σ 2 that is the variance of the sample means multiplied by n (when the sample sizes are the same.). If the samples are different sizes, the variance between samples is weighted to account for the different sample sizes.
