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Critical numbers > Critical numbers > Flashcards

Critical numbers Flashcards

1
Q

What is prevalence probability?

A

Probability of having a disease at a given point in time

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2
Q

Incidence probability

A

Probability of getting a disease during a specified point in time

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3
Q

Incidence rate

A

average rate of change over time

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4
Q

Hazard rate

A

Instantaneous rate of change

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5
Q

Incidence

A

Number of people newly diagnosed

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6
Q

Prevalence

A

new and pre-existing cases

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7
Q

Probability equation

A

P = no. of case/ total population

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8
Q

Odds equation

A

odds = cases/non-cases

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9
Q

Absolute risk definition

A

Difference between 2 risks

e.g. 4 in 100 risk of non-smokers developing a disease

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10
Q

Relative risk definition

A

Ratio between 2 risk

e.g. risk of getting a disease is increased for smokers

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11
Q

What are the 4 different observational studies?

A

1) Cross-sectional
2) Case-control
3) Cohort
4) Ecological

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12
Q

What is a cross-sectional study?

A

Observations made at a specific point in time (now)

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13
Q

Strengths and weaknesses of a cross sectional study?

A

Strengths

  • Fast, inexpensive
  • who currently has exposure and outcome
  • no follow up

Weaknesses

  • not suitable for rare diseases
  • difficult to establish order of events
  • Can’t find causes
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14
Q

What is a case control study?

A

(Past) select participants with and without outcome and look back to see who had exposure

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15
Q

Strengths and weaknesses of case control study?

A

Strengths

  • suitable for rare diseases
  • multiple exposures can be studied
  • quick

Weaknesses

  • only a single disease can be studied
  • difficult to establish order of events
  • affected by selection bias & confounding factors
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16
Q

What is a cohort study?

A

(future)
collect participants info on a sample (some have exposure, others don’t)
Follow up over time, see who gets outcome

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17
Q

Strengths and weaknesses of cohort study?

A

Strengths

  • useful for demonstrating causal effect
  • multiple diseases & exposure can be studied
  • less chance of bias

weaknesses

  • time consuming and expensive
  • not suitable for rare diseases
  • people drop out
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18
Q

What are the 2 experimental studies?

A

Randomised control trial and crossover

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19
Q

What is an RCT? Pros and cons?

A 
Participants randomised to groups and followed up to compare outcomes
Strengths
- 'gold standard'
- prevents bias - can be double blinded
- shows cause and effect
Weaknesses
- expensive
- not suitable for long term effects
- not always ethical 
can be effected by non-compliance
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20
Q

What is a crossover trial? pros and cons?

A

Everyone in the study has all arms of the trial at some point

  • order of each arm randomised
  • everyone is their own comparison

Cons

  • more technical analysis
  • not always suitable (if drug/ surgery has carry over effects)
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21
Q

Association vs causation

A

Association = a statistical link between exposure and disease

Causation = a statistical link where a disease is directly caused by the exposure

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22
Q

What is simple random sampling?

A

Each member of the population has an equal probability of being selected

  • computer generated
  • not always good representation
  • not precise
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23
Q

What is systematic random sampling?

A

Members of the population are selected at equal intervals

cons

  • need complete list of population
  • large standard error
  • periodicity patterns>characteristics that occur at intervals
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24
Q

What is stratified random sampling?

A 
population is split into groups and samples are taken from each group 
Pros
- increases representation
- smaller standard error
cons
- requires prior info about population
- expensive
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25
Q

What is cluster sampling?

A

Population is partitioned into clusters and a sample of clusters is selected (clusters similar)

  • complete list of population not needed
  • cheaper

cons
- clustering decreases statistical precision (higher standard error)

26
Q

Standard deviation vs standard error

A 
SD = within a sample
SE = between samples
27
Q

P -value

A

p < 0.05 indicates statistical significance

28
Q

Crude vs adjusted effects

A

Crude = does not take into account confounding variables

Adjusted = accounts for confounding factors

29
Q

Biochemical, chemical or hormonal stress?

A

Metabolic changes due to stress

- endorphin levels altered

30
Q

Signs of physiological stress?

A

Physiological signs of stress

  • shallow breathing
  • raised blood pressure
  • increase in acid production in the stomach
31
Q

Signs of emotional stress?

A

Emotional signs of stress:

  • mood swings
  • tearful
  • irritable
  • aggressive
  • apathetic
32
Q

Cognitive stress signs?

A
  • Negative thoughts

- loss of concentration

33
Q

Behavioural signs of stress?

A
  • Increases absenteeism
  • smoking
  • alcohol consumption
  • change in food consumption
  • sleep disturbances
34
Q

What are the two types of emotional responses to stress?

A

Positive affect

Negative affect

35
Q

Social signs of stress?

A

Similar to behavioural

  • social relationships
  • participation in activites/work
36
Q

What is primary prevention?

A

prevention of disease in people who have not been diagnosed as having the disease, includes health promotion

37
Q

What is secondary prevention?

A

Early detection of disease

- followed by appropriate intervention

38
Q

What is the high risk approach to prevention?

A

targeting of health promotion and disease prevention at groups based on info from epidemiological studies

39
Q

What is the population approach to prevention?

A

Aims to lower the level of risk in the population, includes health promotion

40
Q

What is tertiary prevention?

A

Aims to reduce the impact of the disease and promotes quality of life through active rehabilitation

41
Q

What is the preventing paradox?

A

A preventive measure which brings much benefit to the population, may offer little to each participating individual

42
Q

What aspect of the relationship between occupation and asthma could only be examined through prospective studies?

a. Association
b. causation
c. analytical
d. descriptive
e. Qualitative

A

B Causation: the existence of a causal relationship between variables; the cause must precede the effect

43
Q

What is an ecological study?

A

Uses routine date from populations

- looks at prevalence, trends and correlations

44
Q

What is a longitudinal study?

A

Observational study of persons over a period of time taking measurements at more than one time point

45
Q

What does it mean if there is a big difference between mean and median?

A

It is not normally distributed

46
Q

If a study is not normally distributed which data should you use?
(e.g. mean, median, SD, SE, IQR)

A

Median

47
Q

What analytical value do you pair with median?

A

IQR

mean and SD

48
Q

Which of the following is incorrect?
The standard error of the mean of a sample:

a. Can be calculated using the standard deviation and the size of the sample
b. Measures how far the sample mean is likely to be from the population mean
c. Is used in the calculation of a confidence interval
d. Is greater than the standard deviation of the observations
e. Should only be calculated when the sample is normally distributed

A

D. The SE will be smaller than the SD

49
Q

What is linear regression?

A

Models the dependency of Y with a change in X

  • can have positive, negative or no correlation
  • can remove background association to reveal a clearer picture of the relationship between the main exposure of interest and outcome
50
Q

What is multi-variable regression?

A

Adjust for all the variables in the model

51
Q

What is opportunity cost?

A

To spend resources on one activity means a sacrifice in terms of a lost opportunity cost elsewhere

52
Q

What is economic efficiency?

A

It is achieved when resources are allocated between activities in such a way as to maximise benefit.

53
Q

What is QALYs?

A

Quality Adjusted Life Year

- combines length of life with quality of life

54
Q

What are the 4 types of economic evaluation?

A 
1) Cost effectiveness analysis 
(measure in natural units e.g. change in BP)
2) Cost-utility analysis 
(measured in QALYs)
3) Cost-benefit analysis
(measure in monetary units)
4) Cost-minimisation analysis
55
Q

Cost effectiveness ratio?

A

Difference in costs/difference in benefits

56
Q

What is observer bias?

A

When variables are reported differently between assessors

57
Q

What is selection bias?

A

error in the process of selecting participants for the study and assigning them to particular arms of the study

58
Q

What is measurement bias?

A

When information is recorded in a distorted manner (inaccurate tool)

59
Q

What is procedure bias?

A

Subjects in different arms of the study are treated differently

60
Q

What is Misclassification bias?

A

Occurs when a variable is classified incorrectly

Critical numbers (1 decks)

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