Study guide

Question 1

What is a ratio, and an example of cases and noncases ?

Answer 1

Ratio = Something/Something (Case/Non-Case)

Question 2

What is proportion, an Example ?

Answer 2

Proportion = Something/Collective (Case/Pop.)

Question 3

What is Rate in terms of people?

Answer 3

Rate = Something/Time or Person (Case/X people or X time)

Question 4

What is incidence in cases? Are they acute or chronic ? What is Attack rate, and who is a risk ? What prevention are there to stop the incidence ?

Answer 4

INCIDENCE New Cases! Incidence = (New Cases)/(Number at risk) Usually ACUTE Infections Attack Rate = Incidence in those with PARTICULAR RISK PRIMARY PREVENTION stops incidence! (prevent infection)

Question 5

What is Prevalence ? What is an example in terms of cases ? What two types of prevalence are there ? Is it for Chronic or acute dieases ? What form of prevention stops prevalence in terms to cure ? What is tertiary prevention ? and what does it improve ? What are some examples ?,

Answer 5

PREVALENCE Current Cases! ( P) present! Prevalence = (ALL CASES)/(Number at risk) 2 types = POINT (At one time) and PERIOD (Span) Prevalence Usually CHRONIC Diseases SECONDARY PREVENTION stops prevalence! (Cures) Note – TERTIARY PREVENTION improves quality of life (example: drugs that extend life, treat, but not cure)

Question 6

How is prevalence/incidence affected when… …A cure is found?

Answer 6

Prevalence down, no change to incidence. since cure happens after infection,

Question 7

A vaccine is found?

Answer 7

Incidence down, prevalence down in time. Since happens before infection

Question 8

therapy extends life?

Answer 8

Prevalence up, no change to incidence. there less pople dying from the current pouplation / people at risk

Question 9

Why are Crude, Specific And Standard Rates used for ?

Answer 9

Important for Population Statistics

Question 10

What is crude rate, and what is it for ?

Answer 10

Crude Rate = All Cases/Total Population

Question 11

What is Specific rate, and what is it for ?

Answer 11

Specific Rate = Cases in Group/Total of Group

Question 12

What is case fatality rate ?

Answer 12

Case Fatality Rate = Death From Cause/Population with Cause

Question 13

What is proportionate mortality rate ?

Answer 13

Proportionate Mortality Rate = Death Due to Cause/All Deaths

Question 14

What is standardized rate for ?

Answer 14

Standardized (Adjusted) Rate: Calculated by adjusting for demographic variable (age, sex, race, etc.)

Question 15

What is Epidemiology to an MD?

Answer 15

Distribution of diseases in a Population. Focus on GROUPS, not INDIVIDUALS Everything is in numbers!! Look at RATIOS and RATES:

Question 16

What is primary care, secondary, and tertiary prevention care ?

Answer 16

Primary prevention aims to prevent disease or injury before it ever occurs. Secondary prevention aims to reduce the impact of a disease or injury that has already occurred. Tertiary prevention aims to soften the impact of an ongoing illness or injury that has lasting effects.elping people manage long-term, often-complex health problems and injuries

Question 17

.Draw the actual sick and diagnosic sick on the diagram.

Answer 17

Question 19

.What are the four total outcomes of the diagram ?

Answer 19

Question 20

.what is the difference between specificity and sensitivity.

Answer 20

Question 21

.Can you calculate the specificity and specialty of this example ?

Answer 21

Question 22

.What is ppv vs npv ?

Answer 22

Question 23

.What is the postive and negetive predicted value ?

Answer 23

Question 24

.What is an example of accuracy in the diagram, and how do you calculate it ?

Answer 24

Question 25

.What is overall accuracy, and how do you calculate it ?

Answer 25

Question 27

What does true and false, and positive and negative mean ?

Answer 27

True= meets both the same result, flase- not the same postive= was shown before to have it negetive = was not shown before ( diagnosed)

Answer 28

ppv and npv depend on the dignognised horizontal super/ super+ part sensity and specifilty depend on healthy and non healthy, vertial

Question 29

¡If we have more cases of the disease, what happens to… ¡…the sensitivity?

Answer 29

NO CHANGE

Question 30

¡the specificity?

Answer 30

NO CHANGE

Question 31

¡the PPV?

Answer 31

INCREASES

Question 32

¡the NPV?

Answer 32

DECREASES

Question 33

Out of the two study types, explain observational.

Answer 33

¡Observational:What is happening in the natural world?

Question 34

Of the second study type, explain experimental ?

Answer 34

¡Experimental What does this intervention cause? After observational studies done. (Clinical Trials)

Question 35

What does case report ? what type of study , is it indivudual or group ? what type of study is it ?

Answer 35

¡Case-Report: N=1,descriptive study, one individual. Most likely if it starts with case, it is observational

Question 36

.Out of three observational studies, case series is a--- study, that looks into ...

Answer 36

¡Case-Series: N\>1, several case-reports combined.

Question 37

In observation studies, case series looks into how many people and what happens to the report ?. What is cross-sectional study based on ? what does it show ? When does it happen, what does it record , does it do associations and causation ? Is there a sign of incidence, and what is it dependent on ?

Answer 37

¡Case-Series: N\>1, several case-reports combined. ¡Cross-Sectional Study: Prevalence Based. - Shows who has what disease. - Happens at fix time. - Records Risk Factor during this time. - Only Associations, not causation! - No sign of Incidence. - Chi squared dependent!

Question 38

Of observational studies, case control study looks at ? It compares ?, what does it asses , and does not ? What is it used for ?. do studies that look back at time for period of time lead to causation or association ?

Answer 38

¡CASE-CONTROL Study: DISEASE vs NON-DISEASE - Compare risk factors in sick versus not sick - Retrospective, - Assess Causality, not Prevalence/incidence - Used for Rarer Diseases, Cheap, Quick. causation

Question 39

Cohor study is a observational study, what does it look at ? is it prospective or retrospective or both ? What does it asses and not, what are the group size ?

Answer 39

¡COHORT Study: EXPOSED vs NON-EXPOSED - Compare diseases in those with/without risk factors. - Prospective, can be retrospective - Assess Incident and causality, not Prevalence. - Large Sample, Expensive, Time-Consuming.

Question 40

.What happens when the postivie and false negitive get bigger ?

Answer 40

Question 41

Explain what is a ROC curve?

Answer 41

Question 42

What are some study types ?

Answer 42

Question 43

How do you calculate for case-control ?. What do you use ?

Answer 43

Question 44

.How do you calculate for cohort study ?.

Answer 44

Question 45

.

Answer 45

How to do calculate a Cohor study

Question 46

answer how do you get OR, RR, and AR ? with a table 90 40 10 60

Answer 46

Question 47

There is another cohort calculation, what is attributable risk ?

Answer 47

¡Attributable Risk: Percent of Cases Due to Exposure AR% =(RR – 1)/RR

Question 48

Number needed to treat (NNT) other cohort calculations . What is it ? What type of questions do they aks ?

Answer 48

¡Number Needed To Treat (NNT): How many people are treated to prevent one case. NNT = 1/AR (Also, NNH: how many harmed?)

Question 49

.Calculate AR, and NNT

Answer 49

Question 50

What are some observation studies- clinical trials ? What is phase 1 -4

Answer 50

Question 51

.

Answer 51

What is baseline will be comparison group, subject randomly assigned double-blind design, and can be crossover design

Question 52

What are two types of error ? which one is unknown influences that unpredictable vs jus not using the right tools and using it wrong .

Answer 52

Question 53

.What are the three things to consider when selection bias ?

Answer 53

Question 54

What are sampling bias? What is non-respondent bias, Ascertainment bias, late-look Bias, and solution-biased.

Answer 54

This has to do with how study population compares to whole population. ¡**Non-Respondent Bias**: Volunteers may be different from those that do not volunteer. Sample Population doesn’t represent non-volunteers ¡**Ascertainment Bias:** Sicker people more likely to enter into treatment and volunteer for studies. Sample population doesn’t represent less sick. **¡Late-Look Bias:** Sicker people who are too sick to participate in study are not included in study. Sample population does not represent the more sick. ¡ **¡Solutions** – Randomize elegible population, weigh the data during analyses (Specific and standardized rates) ​

Question 55

What are sampling bias? What is non-respondent bias, Ascertainment bias, late-look Bias, and solution-biased?

Answer 55

Question 57

What is Measuring bias and of measuring bias, what is Leading Questions ?

Answer 57

¡Leading Questions: How terrible are you? Vs. How would you rank yourself?

Question 58

What is Measuring bias and of measuring bias, what is Hawthorne Effect ?

Answer 58

¡Observer knows they are in a study, behavior changes. Watched = Stress

Question 59

What is Measuring bias and of measuring bias, what is Recall Bias?

Answer 59

¡Recall Bias: Responses incorrect due to poor memory, making things up, distorted view on things.

Question 60

What is Measuring bias and of measuring bias, what is Observer Bias?

Answer 60

¡Observer Bias: Researcher’s past experiences bias study implementation (ie: Psychiatrists think we are all mentally ill.) ¡

Question 61

What is a solution to deal with measuring bias ?

Answer 61

¡Solutions – Make questions easier, use a control group, equally measurements between groups (if skewed, it’s skewed in both groups.)

Question 62

What is Expectancy BIAS?

Answer 62

This is a bias caused by researcher unintentionally.

Question 63

What are two expectancy bias, and what is the solution ?

Answer 63

This is a bias caused by researcher unintentionally. **¡Demand Characteristics**: Behavioral difference by smiling or nodding at certain questions, so to get a specific response. **¡Pygmalion Effect:** Researcher believes his hypothesis is correct. Treats subjects in a way to get a specific results. IE: If I tell my subject that they will do bad on a test, they will score worse. ¡ **¡Solutions** – Double Blind studies, properly trained researchers. ​

Question 64

What is Lead-Time BIAS ? What is the solution ?

Answer 64

¡Earlier Detection is confused with Living Longer! ¡It can happen when new screening method that catch disease earlier, but fail to prevent death. ¡Solution – examine life expectancy to ascertain any bias.

Question 65

What is Proficiency BIAS ?

Answer 65

¡Poorly Implemented Interventions or Treatment. ¡Example – Surgical treatment, different surgeons have different outcomes for the same procedure. ¡Solution – Randomize treatment provider.

Question 66

What is Confounding

Answer 66

¡Hidden causes… ¡Remember the example of coffee and lung cancer? Strong Association between coffee and lung cancer found. When the analysis was redone separating smokers from non-smokers, those who smoked and drank coffee had an association to lung cancer, while the non-smoking coffee drinkers did not… Solution – multiple studies, multiple analyses, and a really good study design.