Important statisitcs Flashcards

1
Q

What is risk? - What is the risk of disease in smokers if 20 smokers in a group of 100 develop the disease?

A

Risk is a percentage. 20/100= 20% of smokers

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2
Q

What is risk ratio?

A

Risk ratio is when you compare the risks of two groups

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3
Q

What is relative risk reduction?

A

Comparing the adverse events in an exposed group vs an unexposed group.

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4
Q

What is experimental event rate?

A

Risk of adverse events in the exposed group.

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5
Q

What is control event rate?

A

Risk of adverse events in control group.

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6
Q

How to calculate relative risk reduction? EER is 94 and CER is 82

A

Experimental event rate- control event rate/ control event rate. Relative risk reduction would be 0.15.

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7
Q

What does relative risk reduction indicate?

A

How much the treatment reduced the risks of an adverse event in exposed group controlled to unexposed group

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8
Q

What is the issue with calclating cumulative risk?

A

It does not takie into account that some people may leave a study or enter it at diferent times due to migration or death so there may be attrition bias. Therefore, incidence rate is used, as it uses person-years which is the sum of each particpant’s entery into the study-> developing disease. Incidence rate is a true rate

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9
Q

How is odds value expressed?

A

As a raw value. Odds cannot be put as a percentage.

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10
Q

What is standard deviation?

A

The range of values around the mean.

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11
Q

What is z value?

A

How many standard deviations a value is from the mean.

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12
Q

What is low standard deviation?

A

Higher accuracy; lower range of values around the mean.

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13
Q

What is high standard deviation?

A

Lower accuracy; greater range of values around the mean.

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14
Q

What is tail of distribution?

A

Extreme regions of distribution in a skewed graph. The area the tail is in indidcates a positive/right skew or negative/left skew.

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15
Q

What is standard error?

A

Approximate standard deviation of a statistical sample population. Measures the variability across different samples in a population.

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16
Q

What is reference range?

A

A range of values that is deemed normal for a physiological measurement in healthy people.

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17
Q

What is confidence interval?

A

Range of values where the true value lie, generally + or - 1.95

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18
Q

What is the meaning of a unimodal graph?

A

Singular peak

19
Q

What is the meaning of a bimodal graph?

A

Two peaks

20
Q

What are the features of a positive skew?

A

Mean and median is greater and to the right, mode stays the same. Median is between the mode and mean.

21
Q

What are the features of negative skew graph?

A

Mean and median is lower and to the left, mode is the same. Median lies between the mode and mean.

22
Q

What is cumulative incidence?

A

Incidence rate in a given time period, such as 5 years. Only consider the incidence on year 1 and year 5 for comparison. Incidence/time period.

23
Q

What is absolute risk?

A

Probability of an event, including both the exposed and the control group.

24
Q

How to calculate absolute risk? Exposed group has 1000 people and 50 people with disease. Control group has 700 people and 56 people with disease.

A

Incidence in Exposed risk +control/ total number in both group. 50+ 56/1000 + 700=0.062 or 6.2% absolute risk.

25
Q

What is meta analysis?

A

Comparing multiple similar studies with a statistical method.

26
Q

What is systematic review?

A

Using rigorous and transparent method to synthesise the data of multiple relevant studies in a single document.

27
Q

What is Phase 1 drug trial?

A

Measure tolerance in healthy participants

28
Q

What is Phase 2 drug trial?

A

Measure efficacy in healthy and diseased participants

29
Q

What is Phase 3 drug trial?

A

Measure efficacy of drug compared to alternative drug

30
Q

What is Phase 4 drug trial?

A

Measure the long term side effects of a drug

31
Q

What is a one tailed graph?

A

Alternative Hypothesis which specifies a postivie or negative effect and goes in one directiion

32
Q

What is a two tailed graph?

A

Alternative hypothesis which does not specify a postivie or negative effect and goes in both directions

33
Q

What is p value?

A

Probability of an outcome occuring if the null hypothesis is true

34
Q

What does a small p value indicate?

A

Reject null hypothesis- Likely the outcome will occur

35
Q

What does a large p value indicate?

A

Do not reject null hypothesis- likely null hypothesis is true

36
Q

What is a competing hypothesis?

A

Alternative hypothesis that goes against another alternative hypothesis

37
Q

What are the databases we use for systematic review?

A

Pubmed, Cochrane library, Google Scholar, NICE, Embase

38
Q

What is a orest plot?

A

Forest plots summarise findings from multiple papers by identifying a common statisitc. It is useful for systematic review and meta analysis,

39
Q

What does the diamond represent in fox plots?

A

Summary of all the data points. Centre is the overall effect estimate and width is the confidence interval

40
Q

What is the value of the vertical line in fox plots?

A

Null effect, which is equal to 1. The closer it is to the null effect, the less significant it is.

41
Q

What is the black box represent in fox plots?

A

Study/point of estimate.

42
Q

What does the line represent in fox plots?

A

95% confidence interval.

43
Q

What is absolute risk reduction?

A

Difference in risk between the placebo and treatment group

44
Q

What is correlational studies?

A

Observational studies to examine event exposure, disease prevalence and risk factors