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Biostatics/Epidemiology > Study guide > Flashcards

Study guide Flashcards

1
Q

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

A

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

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2
Q

What is proportion, an Example ?

A

Proportion = Something/Collective (Case/Pop.)

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3
Q

What is Rate in terms of people?

A

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

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4
Q

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 ?

A

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)

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5
Q

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 ?,

A

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)

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6
Q

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

A

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

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7
Q

A vaccine is found?

A

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

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8
Q

therapy extends life?

A

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

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9
Q

Why are Crude, Specific And Standard Rates used for ?

A

Important for Population Statistics

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10
Q

What is crude rate, and what is it for ?

A

Crude Rate = All Cases/Total Population

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11
Q

What is Specific rate, and what is it for ?

A

Specific Rate = Cases in Group/Total of Group

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12
Q

What is case fatality rate ?

A

Case Fatality Rate = Death From Cause/Population with Cause

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13
Q

What is proportionate mortality rate ?

A

Proportionate Mortality Rate = Death Due to Cause/All Deaths

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14
Q

What is standardized rate for ?

A

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

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15
Q

What is Epidemiology to an MD?

A

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

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16
Q

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

A

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

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17
Q

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

A
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18
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19
Q

.What are the four total outcomes of the diagram ?

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20
Q

.what is the difference between specificity and sensitivity.

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21
Q

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

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22
Q

.What is ppv vs npv ?

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23
Q

.What is the postive and negetive predicted value ?

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24
Q

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

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25
Q

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

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26
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27
Q

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

A

True= meets both the same result,

flase- not the same

postive= was shown before to have it

negetive = was not shown before ( diagnosed)

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28
Q
A

ppv and npv depend on the dignognised horizontal

super/ super+ part

sensity and specifilty depend on healthy and non healthy, vertial

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29
Q

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

¡…the sensitivity?

A

NO CHANGE

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30
Q

¡the specificity?

A

NO CHANGE

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31
Q

¡the PPV?

A

INCREASES

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32
Q

¡the NPV?

A

DECREASES

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33
Q

Out of the two study types, explain observational.

A

¡Observational:What is happening in the natural world?

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34
Q

Of the second study type, explain experimental ?

A

¡Experimental

What does this intervention cause?

After observational studies done.

(Clinical Trials)

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35
Q

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

A

¡Case-Report: N=1,descriptive study, one individual.

Most likely if it starts with case, it is observational

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36
Q

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

A

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

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37
Q

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 ?

A

¡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!
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38
Q

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 ?

A

¡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

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39
Q

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 ?

A

¡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.
40
Q

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

A
41
Q

Explain what is a ROC curve?

A
42
Q

What are some study types ?

A
43
Q

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

A
44
Q

.How do you calculate for cohort study ?.

A
45
Q

.

A

How to do calculate a Cohor study

46
Q

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

10 60

A
47
Q

There is another cohort calculation, what is attributable risk ?

A

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

48
Q

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

A

¡Number Needed To Treat (NNT):
How many people are treated to prevent one case.
NNT = 1/AR

(Also, NNH: how many harmed?)

49
Q

.Calculate AR, and NNT

A
50
Q

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

A
51
Q

.

A

What is baseline will be comparison group, subject randomly assigned

double-blind design, and can be crossover design

52
Q

What are two types of error ?

which one is unknown influences that unpredictable vs jus not using the right tools and using it wrong .

A
53
Q

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

A
54
Q

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

A

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)

​

55
Q

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

A
56
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57
Q

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

A

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

58
Q

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

A

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

59
Q

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

A

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

60
Q

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

A

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

¡

61
Q

What is a solution to deal with measuring bias ?

A

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

62
Q

What is Expectancy BIAS?

A

This is a bias caused by researcher unintentionally.

63
Q

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

A

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.

​

64
Q

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

A

¡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.

65
Q

What is Proficiency BIAS ?

A

¡Poorly Implemented Interventions or Treatment.

¡Example – Surgical treatment, different surgeons have different outcomes for the same procedure.

¡Solution – Randomize treatment provider.

66
Q

What is Confounding

A

¡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.

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Biostatics/Epidemiology (12 decks)

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