Biostadistics

Question 1

Which is the rule 68/95/99?

Answer 1

it is relate with standard deviation:

• 1 SD: 63% of values
• 2 SD: 95%
• 3SD: 99%

Question 2

Precision vs accuracy

Answer 2

Precision: ability of test to produce similar or identical results with repeated measurments (realiability)
Accuracy: Results should be equivalent to results obtained with gold standard. (validity)

Question 3

Absolute risk reduction

Answer 3

AR= (c/c+d) - (a/a+b)

Rate of control - rate of treatment

Question 4

Number needed to harm and atribbutable risk concept?

Answer 4

** 1/ Atribbuible risk
** AR= treatment rate - placebo rate
(Tharm/total) - (Pharm/total)

Question 5

1. Hawthorne bias
2. Berckson bias
3. Pygmalion effect

Answer 5

• “How are you doing?”—- the people know that i observed
• Select bias? —– “ver”
• ” pick” to obtain the result that i want

Question 6

Attrition bias

Answer 6

lost subjects differ in the risk of developing an outcome compared with remaining subjects
- Is a selection bias

Question 7

screening test— sensitive or specificity?

Answer 7

sreening test—- sensitive

specificity— to confirme a positive screening test