BIOSTATISTICS

Question 0

What’s lead time bias?

Answer 0

Is the erroneous finding of prolongation of survival when just the illness was detected earlier .

Question 1

What’s latent period factor in the effect of drugs or change in the risk?

Answer 1

Period needed to show differences

Question 2

What is Observer bias ?

Answer 2

Is when the observer misclassifies data according its interpretation or its expectations

Question 3

What’s selection bias ?

Answer 3

Inappropriate non-random selection

Question 4

When use odds ratio?

Answer 4

CASE-CONTROL STUDIES !!!
RETROSPECTIVE!!!!

OR=ad/bc

“Patients with COPD had higher odds of a
history of smoking than those without COPD.”

Question 5

When use Relative Risk?

Answer 5

COHORT STUDIES!!!!
PROSPECTIVE!!!!!

RR=[a/(a+b)] / [c/(c+d)]
“Smokers had a higher risk of developing COPD
than nonsmokers.”

Question 6

What’s selection bias ?

Answer 6

Selection of unrepresentative sample ( all healthy ,all sick)

ATTRITION BIAS : a very different group of data is loss

Question 7

What’s missclassification bias?

Answer 7

Use the wrong method to classify the groups

Question 8

Big difference between case-control and cross-sectional study?

Answer 8

CASE -CONTROL : Make sick and non-sick subjects

CROSS-SECTIONAL: take random subjects

Question 9

Big characteristic of randomized clinical trial?

Answer 9

COMPARES >2 TREATMENTS

Question 10

What’s type II(beta) error?

Answer 10

Falsely conclude there is NO difference

FALSELY NOT REJECT

Question 11

What’s type I (alpha) error?

Answer 11

Falsely conclude there is a difference

Falsely REJECT

Question 12

The best answer to a college asking about a patient of your is …

Answer 12

No, I cannot say whether she is my patient .

Question 13

How confounding bias can be controlled?

Answer 13

MATCHING
used in case control studies
Matching the subjects by age , race , gender etc…

Question 14

What is statistical power?

Answer 14

1-beta

SAMPLE SIZE

Question 15

Cause of mortality in TCAs overdoses?

Answer 15

Cardiac arrhythmia say inhibit fast Na channels

Refractory hypotension by alpha agonist

Question 16

What is the center of study of ECOLOGICAL STUDY?

Answer 16

COMPARE POPULATIONS!!!!!!!

used to make HYPOTHESIS NOT CONCLUSIONS!!!!

Question 17

What’s nested case-control?

Answer 17

Begins whit cohort studies

The patients with the outcome go to case - control studies

Question 18

How the protest probability affects the NEGATIVE PREDICTIVE VALUE?

Answer 18

⬇️Pre-test probability ⬆️ NPV

⬆️Pre-test probability ⬇️ NPV

Question 19

What is near miss?

Answer 19

Error recognized before any harm

Question 20

What’s sentinels event?

Answer 20

Unexpected event involving death or serious physical or psychological injury that’s REQUIERS IMMEDIATE INVESTIGATION

Question 21

Which calculation can be used to comparete different tests whit different normal values?

Answer 21

Coefficient variance

Question 22

What’s a reliable test?

Answer 22

A test whit very similar results in the same patient is REPRODUCIBLE

Question 23

What’s a valid test ?

Answer 23

Is the ability to measure what is suppose to measure

Very similar whit GOLD STANDARD

Question 24

What’s the attributable risk percent in the exposed?

Answer 24

Percentage of disease attributable to the Exposition

=100x[(RR-1)/RR]

Question 25

What’s referral bias ?

Answer 25

You cannot compared a big specialized hospital whit a small health center even if there is the same illness

Question 26

What’s detection bias?

Answer 26

The risk factor increase the probability of diagnosis because they perform a lot of tests

Question 27

What’s sampling bias?

Answer 27

Very sick people cannot be compared whit sick people not as Ill

Question 28

How calculate the probability of a group of outcomes?

Answer 28

MULTIPLY THE INDEPENDENT EVENTS

Question 29

What is the confidence interval formula?

Answer 29

Mean➕➖Z(S/√N)

Z 95%=2. 99%=2.5
S standard deviation
N population

Question 30

What’s late-Look bias?

Answer 30

Miss severe cases because the patients dye before the study

Question 31

What happen Whit confidence intervals which contain de number 1?

Answer 31

IS NOT STATISTICALLY SIGNIFICAT!!!!!

Question 32

Alpha error is possible ONLY if the p value is….

Answer 32

p<0.05!!!!!

Question 33

When do you use ANOVA, Chi-square test, Meta-analysis , multiplier linear regression, Pearson correlation coefficient, t-test?

Answer 33

ANOVA compare means between 2 or more independent groups

Chi-square test association between 2 categorical variables

Meta-analysis compare a lot of good studies

multiplier linear regression linear relation btw 1 dependent & 2 inde

Pearson correlation coefficient Strength & dirección of linear relation between 2 variables

t-test. Two groups compared

Question 34

What is the equation for number need to treat?

Is equal to number needed to harm NNH…

Answer 34

NNT=1/ARR

Absolute risk reduction = ARR= control %-treatment %

Question 35

What is the Hawthorne and Pygmalion effect?

Answer 35

Hawthorne : observer effect

Pygmalion: all of mine is better

Question 36

Explain which measure two-sample t test, Two-sample z test, Chi-square, Analysis of variance.

Answer 36

two-sample t test 2 groups means
Two-sample z test 2 groups means
Chi-square. 2 categorical variables
Analysis of variance. Means of >2 groups

Question 37

How VPP and VPN are affected by prevalence?

Answer 37

⬆️prevalence ⬆️VPP

⬆️prevalence ⬇️VPN

Question 38

What’s effect modification?

Answer 38

When the outcome is modified by another variable

Ex. Thrombosis in women who take estrogens Vs Thrombosis In SMOKER women who take estrogens

Question 39

Types of distribution?(3)

Answer 39

NORMAL DISTRIBUTION 🔼 mean=median=mode
POSITIVE SKEWED 📉 mean>median>mode
NEGATIVE SKEWED📈 mean<median<mode