Basic - Math/Stats

Question 1

The PT measures the clotting time of the (extrinsic / intrinsic) and common pathways of coagulation

Answer 1

Extrinsic

• involves factor VII
• Short half life 4-6 hrs

Question 2

Vit K dependent factors

Answer 2

1972

10, 9, 7, 2

Question 3

_____ test used where there is ONE population with respect to TWO variables w/ NUMERICAL data
- ie: subject’s BP are measured prior to a tx for HTN, and same subjects are tested again after tx

Answer 3

Paired T test

Question 4

____ test used to compare TWO populations with respect to SINGLE variable w/ NUMERICAL data
- ie: MAP (single variable) of one group of pts receiving IV labetalol, and a separate group receiving IV hydralazine

Answer 4

Unpaired T test

Question 5

____ test is used for comparison of TWO or more populations with respect to a SINGLE variable with CATEGORICAL data

Answer 5

Chi-square

Question 6

POWER = ?

Answer 6

1-Beta

Chance of correctly rejecting the null hypothesis (Ho) when the alternative hypothesis (Ha) is actually true

Question 7

How to calculate Standard error of the mean (SE)?

Answer 7

Std Deviation / square root sample size

Question 8

In a normal distribution (68%, 95%, 98%), what % is the data greater than one std deviation to the RIGHT (or left) of the mean?

Answer 8

16%

*One std dev to the R is 13.6%
Two std dev to the R is 13.6% + 2.1% = (15.9%)
3 Std dev to the R is 13.6% + 2.1% + 0.2% = (16%)

Question 9

Ways to increase power?

Answer 9

1. Increase alpha (decrease type II error)
2. Decrease population variability
3. Increase sample size
4. Make diff btwn conditions greater (decrease type II error)

Question 10

What test do you want to use when you want to:
Compare 2 diff groups:
Compare more than 2 diff groups:
Compare 2 paired groups:

Answer 10

Compare 2 diff groups: Two sample (unpaired) T-test or Chi squared
Compare more than 2 diff groups: one way ANOVA
Compare 2 paired groups: Paired T test

Question 11

Primary theory of IV regional anesthesia?

Answer 11

LA through the vascular bed reaching peripheral nerves

Question 12

What type of data does chi square test compare?

Answer 12

nonparametric test to compare nominal or ordinal data

ordinal (categorical)

• pain score
• Annual income

nominal data

• gender
• eye color
• occupation

Question 13

What is a type 1 error?

Answer 13

False Positive

• incorrectly accepting alternative hypothesis Ha
• alpha error

Question 14

What is a type 2 error?

Answer 14

False negative

• incorrectly accepting null hypothesis Ho
• beta error

Question 15

Most factors are reduced in liver disease, which ones are INCREASED?

Answer 15

Factor VIII and vWF

- produced extra-hepatically in endothelial cells

Question 16

What should plt count and fibrinogen be in a pt with liver disease undergoing

• high risk surgery
• gen surgery

Answer 16

• high risk surgery: > 100
• gen surgery: 50-60

Fibrinogen > 100