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USMLE Step 1 Mnemonics Mnemonics, acronyms, reminders, and memorizing tips for the USMLE Step 1.


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  #1  
Old 10-21-2009
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Stats Odds Ratio

The formula for odds ratio is easily remembered

The years can either be AD or BC
AD = Anno Domini, After christ
BC = Before Christ

The odds ratio
OD = AD/BC

Of course remember that the A cell is always the disease with the risk and then simply cross to the D cell and divide by the other two cells.

So for example in this 2X2 table
The AD cells are in red and the BC cells are in yellow
The A cell is the number of males with stroke.

Odds Ratio-2x2.jpg
click image to enlarge

Note in the case of Odds ratio we are measuring the likelihood that a stroke patient is being a male (risk factor) and not the reverse (we are not measuring the probability of getting a stroke if the patient is a male).
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Old 12-11-2009
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Default Caution

I've seen an NBME question that requires the knowledge of this formula
A/C divided by B/D
so the mnemonic of AD/BC is not always useful.
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Old 01-22-2011
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Default

Quote:
Originally Posted by rasheed View Post
I've seen an NBME question that requires the knowledge of this formula
A/C divided by B/D
so the mnemonic of AD/BC is not always useful.
Isn't that the same thing in the end?
A/C divided by B/D
=
A/C times D/B
=
AD/BC

I think your mnemonic is pretty good
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Old 04-28-2011
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"Not in the case of Odds ratio we are measuring the likelihood that a stroke patient is being a male (risk factor) and not the reverse".

what do you mean by" not the reverse"??
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Old 04-28-2011
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Quote:
Originally Posted by life9 View Post
"Not in the case of Odds ratio we are measuring the likelihood that a stroke patient is being a male (risk factor) and not the reverse".

what do you mean by" not the reverse"??
Odds Ratio: measuring the odds of a risk factor when you already have the disease, i.e. you already have stroke, what's the likelihood that it was caused by male sex. It starts with the disease and ends with risk factor.

While Relative Risk and Attibutable Risk: it starts with the risk factor and ends with the disease, i.e. if you are male then what's the likelihood you'll get stroke.
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Biostatistics-Epidemiology

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