Biostatistics #15 - Outbreak of gastritis - USMLE Forums
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Old 06-08-2011
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Stats Biostatistics #15 - Outbreak of gastritis

An outbreak of gastritis occurred on a cruise ship. The data in table were obtained, shortly after the outbreak, from a questionnaire completed by everyone on board the ship.

cruise ship.bmp

1. What is the most likely infective food on the cruise ship?
a. herring
b. chicken
c. spinach souffle
d. oysters
e. chocolate mousse

2. What is the relative risk of developing gastritis for herring consumption?
a. 0.5
b. 2.0
c. 2.3
d. 8.0
e. 5.0
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Old 06-08-2011
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1- obviously you dont like chicken , sushi fan perhaps?

2- RR= 2?
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Old 06-08-2011
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my answers are b & b
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Old 06-08-2011
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Quote:
Originally Posted by bebix View Post
An outbreak of gastritis occurred on a cruise ship. The data in table were obtained, shortly after the outbreak, from a questionnaire completed by everyone on board the ship.

Attachment 1462

1. What is the most likely infective food on the cruise ship?
a. herring
b. chicken
c. spinach souffle
d. oysters
e. chocolate mousse

2. What is the relative risk of developing gastritis for herring consumption?
a. 0.5
b. 2.0
c. 2.3
d. 8.0
e. 5.0
my answers..
1.B (highest odd ratio..16.7)
2.B
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Old 06-08-2011
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1. not sure
2. RR 2
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Old 06-08-2011
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1. not sure , chicken perhaps?
2. RR 2
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  #7  
Old 06-08-2011
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Correct Answer correct answer

1 - B)

2 - B)

In question one, you could calculate OR or RR
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Old 06-08-2011
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Quote:
Originally Posted by bebix View Post
1 - B)

2 - B)

In question one, you could calculate OR or RR
can u tell me how u do that in 1? i m very very bad in stats.
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Old 06-08-2011
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Quote:
Originally Posted by pass7 View Post
can u tell me how u do that in 1? i m very very bad in stats.
I did the same thing that you did when you calculated the RR for qs # 2

In this case we have herring, chicken, spinach...

So, for herring the RR is:
Risk people who ate = 200/1000
Risk people did not eat = 100/1000

RR = (200/1000) / (100/1000) = 2

for chicken
RR = (650/1000) / (100/1000) = 6.5...and then with spinach, oysters & chocolate....
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