Fiser Chapter 44 STATISTICS

Question 1

Meta-analysis

Answer 1

combines data from different studies

Question 2

RCTs avoid ____

Answer 2

avoids treatment biases

Question 3

Promoting culture of safety

Answer 3

Confidential system of reporting errors
Emphasis on learning over accountability
Flexibility in adapting to new situations or problems

Question 4

Case-control study

Answer 4

Those who have disease are compared with those who do not

Compare frequency of suspected risk factor

Retrospective

Question 5

Paired t tests

Answer 5

Before and after studies (weight before and after, drug versus placebo)

Quantitative

Question 6

p

Answer 6

null hypothesis rejected

> 95% likelihood that the difference between the populations is true

AKA

Question 7

Parameter

Answer 7

population

Question 8

Kaplan-Meyer

Answer 8

estimates survival in small groups

Question 9

NPV

Answer 9

TN / (TN + FN)

Question 10

Relative risk

Answer 10

incidence in exposed / incidence in unexposed

Question 11

Variance

Answer 11

spread of data around a mean

Question 12

Sensitivity

Answer 12

TP / (TP + FN)

Question 13

Student’s t test

Answer 13

Compares means between 2 independent groups

Quantitative

Question 14

Accuracy

Answer 14

???

Question 15

Sentinel event

Answer 15

Unexpected occurrence involving death or serious injury, or risk thereof

Hospital undergoes root-cause analysis to prevent and minimize future occurrences

eg wrong site surgery

Question 16

Risk factors for retain object

Answer 16

Emergency procedure
Unplanned change in procedure
Obesity
Towel used for closure

Question 17

Chi-squared test

Answer 17

Compares 2 groups with categorical variables

e.g. number of obese patients with and without diabetes versus number of nonobese patients with and without diabetes

Question 18

GAP protection technique

Answer 18

gaps in care (eg change in caregiver, divisions of labor, shift changes, transfers) can lead to loss of information and error

Prevention: structured handoffs and checklists (face to face if possible); standardizing orders; reading back orders if verbal

Question 19

Type 1 error

Answer 19

no difference (but thinks there is)

Question 20

Mean

Answer 20

average

Question 21

Incidence

Answer 21

Number of new cases diagnosed over a certain time frame in a population

Question 22

Specificity

Answer 22

TN / (TN + FP)

Question 23

Mode

Answer 23

most frequently occurring value

Question 24

Median

Answer 24

middle value (50th %ile)

Question 25

Cohort studies

Answer 25

compare disease rate between exposed and unexposed groups

Nonrandom

Prospective

Question 26

ANOVA

Answer 26

Compares means between more than 2 groups

Quantitative

Question 27

Power of test

Answer 27

Probability of making correct conclusion

1 - probability of type 2 error
1 - probability of not seeing difference when there is one

Likelihood that conclusion is true
Larger sample size increases power

Question 28

Nonparametric statistics

Answer 28

compares categorical (qualitative variables)

E.g. race, sex, medical problems, medications

Question 29

Predictive values depend on ___

Answer 29

disease prevalence

Question 30

Type 2 error

Answer 30

there’s a difference (but don’t see it)

due to small sample size

Question 31

Prevalence

Answer 31

number of people with disease in a population

higher in chronic diseases

Question 32

Double-blind controlled trial avoids ____

Answer 32

avoids observational biases

Question 33

PPV

Answer 33

TP / (TP + FP)

Question 34

JCAHO prevention of wrong site/procedure/patient protocol

Answer 34

Time out before incision
Pre-op verification of patient and procedure
Operative site and side
Availability of implants or special requirements