epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evidenc ...

and

biostatistics Biostatistics (also known as biometry) are the development and application of statistical methods to a wide range of topics in biology. It encompasses the design of biological experiments, the collection and analysis of data from those experime ...

, the experimental event rate (EER) is a measure of how often a particular statistical event (such as response to a drug,

adverse event An adverse event (AE) is any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. An adverse event can ther ...

or death) occurs within the experimental group (non-control group) of an experiment. This value is very useful in determining the therapeutic benefit or risk to patients in experimental groups, in comparison to patients in

placebo A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like Saline (medicine), saline), sham surgery, and other procedures. In general ...

or traditionally treated control groups. Three statistical terms rely on EER for their calculation:

absolute risk reduction The risk difference (RD), excess risk, or attributable risk is the difference between the risk of an outcome in the exposed group and the unexposed group. It is computed as I_e - I_u, where I_eis the incidence in the exposed group, and I_u is the ...

relative risk reduction In epidemiology, the relative risk reduction (RRR) or efficacy is the relative decrease in the risk of an adverse event in the exposed group compared to an unexposed group. It is computed as (I_u - I_e) / I_u, where I_e is the incidence in the expo ...

and

number needed to treat The number needed to treat (NNT) or number needed to treat for an additional beneficial outcome (NNTB) is an epidemiological measure used in communicating the effectiveness of a health-care intervention, typically a treatment with medication. The ...

Control event rate

The ''control event rate (CER)'' is identical to the experimental event rate except that is measured within the scientific control group of an experiment.

Worked example

In a trial of hypothetical drug "X" where we are measuring event "Z", we have two groups. Our control group (25 people) is given a

, and the experimental group (25 people) is given drug "X". Event "Z" in control group : 4 in 25 people

Control event rate In epidemiology and biostatistics, the experimental event rate (EER) is a measure of how often a particular statistical event (such as response to a drug, adverse event or death) occurs within the experimental group (non-control group) of an experi ...

: 4/25 Event "Z" in experimental group : 12 in 25 people Experimental event rate : 12/25 Another worked example is as follows:

References

Biostatistics Epidemiology Medical statistics Statistical ratios {{statistics-stub

Control event rate

Worked example

See also

References