Research methods/ stats/ethics/Canmeds

Question 1

What is specificity

Answer 1

The ability to confirm absence of the disease

true negative rate

Question 2

Positive predictive valve

Answer 2

the probability of disease if the test is positive

Question 3

Negative predictive value

Answer 3

Is the probability of absence of disease if the test is negative

Question 4

What is null hypothesis

Answer 4

defined as lack of difference between the two treatments

Question 5

What is a type 1 error

Answer 5

rejecting the null hypothesis when it is true
False positive rate
Occurs when a statistically significant difference is found, when really there is no difference
It is based on the choice of the level of statistical significant p < 0.05

Question 6

What is a type 2 error

Answer 6

not rejecting the null hypothesis when it is false
Chance that the study finds no difference when in fact there is a difference
Chance of a type II error is inversely related to the sample size and to the statistical power

Question 7

List Bias associated with meta anlalysis studies

What techniques can be done to reduce bias?

What technique to test for Heteogenity

List 2 strengths of Metanlysis

Answer 7

1. Publication bias/Search Bias/Selection bias
2. “Funnell plot”
3. Forest Plot–and a subsequent cochran Q- test
4. Strengths:
   a. Increased Effective sample size which greatly increases more outcomes and variable that can be examined
   b. Allows examining of rare events

Question 8

What is major strength of RCT compared to Observational study?

List 2 ways that Observational studies attempt to account for weakness

List 3 potential limitations of RCT

Answer 8

RCT eliminates selection bias

Propensity analysis and Risk adjustment techniques (such as regression or analysis of variance)

weakness of RCT

a. decreased generalizability--specific inclusion/exclusions
b. Inadequate statistical power --expensive to enroll pts
c. Follow-up and approach to treatment may not be representative of real life

Question 9

What is c statistics

Answer 9

probability that predicting the outcome is better than chance.

Used to compare the “goodness of fit” of logistic regression models, values for this measure range from 0.5 to 1.0.

value of 0.5 indicates that the model is no better than chance at making a prediction of membership in a group and a value of 1.0 indicates that the model perfectly identifies those within a group and those not.

Models considered reasonable when the C-statistic is higher than 0.7 and strong when C exceeds 0.8

Question 10

What is p value

Answer 10

p-value is the probability of obtaining a test statistic at least as extreme as the one that was actually observed, assuming that the null hypothesis is true. One often “rejects the null hypothesis” when the p-value is less than the predetermined significance level which is often 0.05 or 0.01, indicating that the observed result would be highly unlikely under the null hypothesis. Many common statistical tests, such as chi-squared tests or Student’s t-test, produce test statistics which can be interpreted using p-values.

Question 11

What is null hypothesis

Answer 11

the null hypothesis refers to a general or default position: that there is no relationship between two measured phenomena,or that a potential medical treatment has no effect.Rejecting or disproving the null hypothesis – and thus concluding that there are grounds for believing that there is a relationship between two phenomena or that a potential treatment has a measurable effect – is a central task in the modern practice of science, and gives a precise sense in which a claim is capable of being proven false.

Question 12

What is C statistic

Answer 12

A measure that indicates how well a prediction model or risk score discriminates between pts who do and who do not have an event.

e.g., “how well a value (predicted lactate clearance) is able to discriminate between patients who had an event (death, MI, etc)

A C-statistic is good if it’s greater then 0.8 as a good utility, valves from 0.7 to 0.8
A value of 1.0 is assigned to a prediction model or risk score with a perfect ability to discriminate between pts who do and do NOT have an event

Question 13

What’s type I error an type II error

Answer 13

Itype I error (or error of the first kind) is the incorrect rejection of a true null hypothesis. A type II error (or error of the second kind) is the failure to reject a false null hypothesis. A type I error is a false positive. Usually a type I error leads one to conclude that a thing or relationship exists when really it doesn’t.
A type II error is a false negative.

When comparing two means, concluding the means were different when in reality they were not different would be a Type I error; concluding the means were not different when in reality they were different would be a Type II error.

Question 14

What is odds ratio

Answer 14

The odds ratio is a measure of effect size, describing the strength of association or non-independence between two binary data values. It is used as a descriptive statistic, and plays an important role in logistic regression. Unlike other measures of association for paired binary data such as the relative risk, the odds ratio treats the two variables being compared symmetrically, and can be estimated using some types of non-random samples.

Question 15

What is relative risk

Answer 15

In statistics and mathematical epidemiology, relative risk (RR) is the risk of an event (or of developing a disease) relative to exposure. Relative risk is a ratio of the probability of the event occurring in the exposed group versus a non-exposed group

In a simple comparison between an experimental group and a control group:
A relative risk of 1 means there is no difference in risk between the two groups.
An RR of < 1 means the event is less likely to occur in the experimental group than in the control group.
An RR of > 1 means the event is more likely to occur in the experimental group than in the control group.

Question 16

If a patient is incapable of a decision the order of who is selected is?

What ethical principle justifies not obtaining informed consent

Answer 16

A person specified by the patient when capable 
A court appointed person
A spouse
A child
A brother
relative or friend

Beneficence is the ethical principle

Question 17

The standards of disclosure in western legal systems

Answer 17

Professional standard: what other physicians tell the patient
Reasonable person standard: what a reasonable person would want to know.
Particular person standard: What a reasonable person in the particular circumstance as the patient would want to know

Question 18

What is Survival Analysis

Answer 18

involves the modeling of time to event data; in this context, death or failure is considered an “event” in the survival analysis literature – traditionally only a single event occurs for each subject, after which the organism or mechanism is dead or broken.

Question 19

What is Hazard ratio

Answer 19

In survival analysis, the hazard ratio (HR) is the ratio of the hazard rates corresponding to the conditions described by two levels of an explanatory variable.

Example, in a drug study, the treated population may die at twice the rate per unit time as the control population. The hazard ratio would be 2, indicating higher hazard of death from the treatment. Or in another study, men receiving the same treatment may suffer a certain complication ten times more frequently per unit time than women, giving a hazard ratio of 10

Question 20

What is major strength of RCT compared to Observational study?

List 2 ways that Observational studies attempt to account for weakness

List 3 potential limitations of RCT

Answer 20

RCT eliminates selection bias

Propensity analysis and Risk adjustment techniques (such as regression or analysis of variance)

weakness of RCT

a. decreased generalizability--specific inclusion/exclusions
b. Inadequate statistical power --expensive to enroll pts
c. Follow-up and approach to treatment may not be representative of real life

Question 21

What are key aspects of PROFESSIONAl

Answer 21

Committed to the health and well-being of individuals and society through ethical practice, profession-led regulation, and high personal standards of behaviours
Comitment to clinical competence, the embracing of appropriate attitudes and behaviors, integrity, altriusm, personal well being and to the promotion of the public good within their domain

Question 22

What is major strength of RCT compared to Observational study?

List 2 ways that Observational studies attempt to account for weakness

List 3 potential limitations of RCT

Answer 22

1. Publication bias/Search Bias/Selection bias
2. “Funnell plot”
3. Forest Plot–and a subsequent cochran Q- test
4. Strengths:
   a. Increased Effective sample size which greatly increases more outcomes and variable that can be examined
   b. Allows examining of rare events

Question 23

Describe levels of Evidence

Answer 23

level A evidence = data derived from multiple randomized trials or metal-analyses
Level b: data from single randomized trial or non randomized trial
Level c: only consensus opinion from experts

Question 24

Five Conditions that must be met for ethical research

Answer 24

A: The existence of clinical equipoise
A: Good design
A: Sound foundation of previous work must give good reason to believe that the proposed interventions will achieve the intended result
A: Research interventions are not likely to cause tserious harm to the research subjects
A: Prior approval by a Research Ethics Board

Question 25

Define clinical equipipose

Answer 25

This exists when the expert medical opinion remains divided over the best choice among treatment options; the medical community is unable to achieve consensus on the preferred treatment

Question 26

Distinguish euthanasia and assisted suicide from decisions to forego treatment

Answer 26

A: Euthanasia and assisted suicide involve the injection of a lethal substance or the provision of a lethal overdose A: Decisions to forego treatment involve the non-initiation or discontinuation of a life-sustaining treatment such as CPR, ventilator, tube feeding, etc. The law permits discontinuation, even though it leads to death, under defined conditions

Question 27

Define competence

Answer 27

A: Possession of the required knowledge, skill, and experience to perform a particular task reliably and produce an appropriate outcome A: It is a categorical variable; one is competent, or not, to provide a particular service or perform a particular operation

Question 28

What are the elements of informed consent

Answer 28

Capacity: the patient is able to understand the risks and benefits of treatment vs non-treatment Voluntariness: The patient is not subjected to coercion Disclosure: the patient is informed enough to give consent the right to accept or refuse treatment is preserved by the charter of rights in canada

Question 29

Q: What are the 3 standards for how the decision should be made, in decreasing order of priority?

Answer 29

A: Wishes – Prior expressions by the patient, while competent that seem to apply to the actual decision that needs to be made A: Values and beliefs A: Best interests – This is more important for children, where the decision maker is usually the parent; decisions should be respected unless they would cause direct and serious harm to the child

Question 30

Q: What are the 3 important aspects to informed consent as per the Royal College?

Answer 30

A: Disclosure – Information about the risks and benefits of the proposed test or treatment as well as any alternatives, presented in language that the patient can understand A: Capacity – The ability to understand and appreciate the consequences of a particular decision or lack of decision; If in doubt, consultation from a psychiatrist, hospital attorney, or ethicist may be helpful, the ultimate judge of a patient's capacity is court; If the patient is incapable, seek consent from the appropriate substitute decision maker A: Voluntariness – The ability to make treatment choices without undue external coercion

Question 31

What are the 7 CanMEDS

Answer 31

``` Scholar Manager Health Advocate Collaborator Communicator Professional Medical expert ```

Question 32

Q: What are the 7 CanMEDs roles?

Answer 32

A: Medical expert – Diagnostic and Therapeutic skills, effective patient care, access and apply information, consultation A: Communicator – Therapeutic relationship, relevant history, listen effectively, discuss appropriate information A: Collaborator – Consult effectively, multidisciplinary team A: Manager – Utilize and allocate resources, health care organization, use information technology A: Scholar – CME, facilitate learning, critically appraise the literature, contribute to new knowledge A: Health advocate – Identify determinants of health, for patients and community, recognize and respond A: Professional – Integrity, honesty, and compassion, interpersonal behaviours, practice medicine ethically consistent with obligations

Question 33

List key issues of SCHOLAR

Answer 33

life long commitment to reflective learning, as well as creation, dissemination, application and translation of medical knowledge Pursuit of matering their domain of expertise, crtical appraise sources of medical info Facilitate the education of their students, pts, colleagues, new knowledge,

Question 34

List 8 principles of ethics

Answer 34

Autonomy--persons right to self rule Beneficence--promote well being of others Confidentiality--persons right to decide how and to whom information is communicated Covenant-binding agreement between two or more parties Fiduciary relationship- relationship founded on faith and trust Informed consent-- Justice-- Maleficience--the act of committing hard

Question 35

List barriers to obtaining consent in non-english pt

Answer 35

``` Disclosre Accuracy Autonomy voluntariness Impartiality Capacity/competency Doctor-patient confidentiality ```

Question 36

List exceptions to the doctor-patient confidentiality act

Answer 36

A Third party who may be harmed should be informed Spousal or child abuse must be reported to authorities Some communicale diseases must be reported to health authorities

Question 37

What is confidentiality

Answer 37

the right to privacy prohibits and MD from revealing information unless pt waives privledge HIPPA--Health care information Privacy and protection Act Legal Issues--if neccessary to avert danger to others, or the needs of society

Question 38

4 Reasons why you have to tell a pt about an operation

Answer 38

Autonomy: pt has freedom to choose own path Fidelity: trusting theapeutic relationship with pt Veractiy: truthfulness with pt Disclosure: Therapeutic privilege:

Question 39

What is required for Informed Consent

Answer 39

``` Nature of Procedure Benefits/Objectives Alternatives Clear indications for surgery Risks/Possible complications ```

Question 40

What are important aspects of collaborator

Answer 40

Work within a healthcare team to achieve optimal patient care Collaborate with interprofessional health care team Work to resolve interprofessional conflict

Question 41

List key aspects of Communicator

Answer 41

Physicians effectively facilitate the doctor patient relationship and the dynamic exchanges that occur before, during, and after the medical encounter Shared decision-making and effect dynamic interactions with patients, families, caregivers, other professionals, and important other individuals Rapport and trust, ethical therapeutic relationships with patients convey relevant information to collegues

Question 42

List important aspects of MANAGER

Answer 42

1. work as individuals, as members of teams or groups, as participants in the health system locally, reigionally and nationally. 2 prioritize, execute tasks collaboratively with colleagues, and make systematic choices when allocating health care resources. 3. manage their practice and career effectively 4. Employ information technology, life-long learning

Question 43

List Key aspects of Health Advocate

Answer 43

use their expertise and influence to advance the health and well-being of individual patients, communities, and population recognize their duty and ability to improve the overall health of their patients and the society t Health promotion, recognize to determinants of Health

Question 44

What are major point of Medical Expert

Answer 44

Integrate all the CanMEDS in a patient centered care Body of knowledge, clinical skills, procedural skills, and professional attitudes apply knowledge to collect interpret information and make appropriate clinical decisions Function as consultants

Question 45

What are weakness of Randomized Controlled Trials

Answer 45

Expensive Feasibility Ehthical Issue Possible lack of external valdity - ability to generalize to overall population - strict/inclusion exclusion - participants enrolling may be different then those that don't agree "Volunteer Bias"

Question 46

Strengths RCT

Answer 46

Provides greatest strength of causal inference Optimal methodology to rest efficacy of a treatment program Protects against selection bias and known and unknown confounding variables Double blinding - ascertainment bias - diagnostics suspicion bias - Detection bias Method of choice to evaluation small/modest effects The 2 groups are equal at baseline

Question 47

Describe 3 times of analytical observation studies

Answer 47

Cohort--retrospective or prospective Case-Control- by definition its retrospective Cross-section- "snap shot" in time

Question 48

Describe a Cohort study design

Answer 48

Retro-looks at exposure and then finds the outcome in charts prospective- takes a group that is exposed and another group that is unexposed and follows them forward. Can attempt to control for confonding variable by 1) Stratifying 2) Multi-variable analysis

Question 49

Disadvantages of Cohort

Answer 49

More subjective to systemic error then RCT (weaker at establishing causation) Baseline characteristics are not equal--cannot be blinded Detection bias--increased chance of detecting an abnormality Selection bias--pt who choose one thing over another differ at baseline Strength of association cannot be provided as evidence of causation

Question 50

What is details of Case-control study design

Answer 50

"begins at the end" patient selection is based on whether or they have the disease or outcome Design is retrospective by definition Typically 1 ours Advantage - More efficient for addressing an assoication between rare outcomes and exposre of interest - can be done quickly - less expensive

Question 51

What disadvantages of case control study design

Answer 51

``` Easy to do poorly only one outcome can be measured Prone to Bias observer bias recall bias selection bias Difficult to choose appropriate control group can't calculated incidence or prevalence Confounding effects Difficult to establish cause and effect ```

Question 52

List 2 descriptive observational studies and advantages

Answer 52

Case series Case report No comparison group/least sophisticated study design good for highly unusual cases or series Valuable information on: frequency, natural history, possible determinats of condition general hypothesis

Question 53

List 3 types of Systemic reviews

Answer 53

Meta-Analysis Decision Analysis Economic Analysis

Question 54

Define Decision Analysis

Answer 54

quantitative approach to evaluate relative values of different management options --each outcome is assigned a probability based on a review of the literature and medical expertise, then these probabilities are statistically analyzed

Question 55

Describe Economic Analysis

Answer 55

Focus on cost COST-BENEFIT analysis--the costs of medical care and the benefits of reduced loss of net earnings due to preventing premature death or disability are considered COST-EFFECTIVENESS analysis--determine the costs and effectiveness of an activity or to compare similar alternative activities to determine the relative degree to which they will obtain the desired objectives or outcomes

Question 56

Define selection bias

Answer 56

subjects in the sample are not representative of the population (non random sampling), pts characteristics have an impact on outcomes other than those being studies

Question 57

Define recall Bias

Answer 57

relying on a subjects memory with respect to exposure or outcomes

Question 58

Ascertainment bias

Answer 58

systemic failure to present equally all classes or persons supposed to represented in the sample

Question 59

Detection bias

Answer 59

bias due to systemic errors in methods of ascertainment, diagnosis or verification of cases in an epidemiologic study

Question 60

What are confounders

Answer 60

the illusory association between 2 variable when in fact there is no association--it is caused by a third variable which is correlated with the first two

Question 61

What is Criteria for Causation (Bradford Hill)

Answer 61

1. Strength of Association--How larges is the effect 2. Temporal relationship- does the cause precede the effect 3. Consistency--study findings consistent over numerous reports 4. Biologic plausibility--does the relationship make biological sense 5. Biogloic-gradient--is there a dose-response relationship 6. Evidence: Is there experimental evidence to support or refute the association 7. Specificity: does altering only the cause alter the effect 8. Coherence--does the evidence fit with what is known regarding the history and biology of the outcome 9. Reasoning analogy-- is the observed association supported by similar associations

Question 62

What are types of validity

Answer 62

Internal Validity External Validity Construct Validity Statistical conclusion validity

Question 63

What is Validity

Answer 63

Degree to which the inferences drawn from the study are warranted when account is take of the study methods, the representativeness of the study sample and the nature of the population from which it is drawn

Question 64

What is is External Validity

Answer 64

the generalizability is the degree to which the results of an observation hold true in other settings (does it apply to my practice)

Question 65

What is Internal validity

Answer 65

The degree to which the results of an observations are correct for the patients being studied

Question 66

Define Reliability

Answer 66

the extent to which repeated measurements of a relatively stable phenomenon fall closely to each other

Question 67

List 4 things you need for a sample sized calculation

Answer 67

Alpha Error Beta Error Standard deviation Minimally clinically important difference

Question 68

What is a study's power

Answer 68

``` The ability to detect an association when one truly exists type II error = 1 - POWER Power increases as sample size increase Is determined by a. Frequency of condition under study/prevalance b. magnitude of the effect c. the study design d. the sample size ```

Question 69

What is Likelihood ratio

Answer 69

likelihood that a given test result would be expected in a patient with the target disorder compared to the likelihood that the same result would be expected in a patient without the target disorder assess how good a diagnostic test is, and to help in selecting appropriate diagnostic tests

Question 70

What is Number needed to Treat

Answer 70

the reciprocal of the change in the absolute risk brought about by an intervention (if risk reduction is 0.5 then NNT = 1/0.5 = 2. No set limit to be considered clinically effective, but generally the lower the better

Question 71

Describe confidence intervals

Answer 71

An indication of variability of a point estimated In general the wider the CI the less precise the point estimate A 95% CI means that there is a 95% that this elevated or decreased risk not due to chance

Question 72

List 3 measurements of central tendency of descriptive stats

Answer 72

Mean--average-- Median-the value with half the subjects below it and half the subjects above it Mode--for Nominal data--most frequently reported

Question 73

List two measurements of variance

Answer 73

Standard deviation--determines on average how much the individual values differ from the mean Standard error--describes the distribution of the mean value== SD divided by the square root of the same size.

Question 74

List 4 tests for assessing continuous data, assumed to following a bell curve

Answer 74

T-test--2 groups of continuous data unpaired t-test--independent samples paired-2 paired observations on the same individual or matched pats ANOVA--comparison of two or more sample means ANCOVA--combines regression and anlysis of variance

Question 75

List Non Parametric tests

Answer 75

``` 1. Ordinal data and independent samples Mann-Whitney-U test Krusak Wallis test 2. Ordinal data, matched samples Wilcoxon test 3. Freidmans 2 way ANOVA ```

Question 76

List tests for Proportions

Answer 76

For nominal data and independent samples Chi-squared (typically proportions) Fishers Exact test (use if one of the values as a 0) Binominal test

Question 77

What is Linear regression and linear correlation

Answer 77

Linear regression analyzes the relationship between 2 variables --X and Y and attempts to find the best straight line through the data (assumes the data is Gaussian/normal) goal is to find the line that best predicts Y from X "Goodness of fi" = r2= it calculates how well the least squares regression line fits a given set of paired data--is a number between 0.0 and 1.0, if r2 is 0.0 then there is no linear relationship between X and Y, if it 1.0 then Y can be predicted perfectly from X

Question 78

What is a Logistic regression analysis

Answer 78

Most common example of multi-variable analysis Statistical tool used to evaluation simultaneously the relationship of many variable (confounders) to the outcome of interst

Question 79

What is equation for sensitivity

Answer 79

A/A + C

Question 80

What is Specificity equation

Answer 80

B / B + D

Question 81

What is Sensitivity

Answer 81

The ability to confirm the presence of disease | true positive rate, or the recall rate