Control event rate

In epidemiology and biostatistics, the control event rate (CER) is a measure of how often a particular statistical event (such as response to a drug, adverse event or death) occurs within the scientific control group of an experiment ^[1].

This value is very useful in determining the therapeutic benefit or risk to patients in experimental groups, in comparison to patients in placebo or traditionally treated control groups.

Three statistical terms rely on CER for their calculation: Absolute risk reduction, Relative risk reduction and Number needed to treat.

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 placebo, and the experimental group (25 people) is given drug "X".

Event "Z" in control group : 4 in 25 people Control Event Rate : 4/25

Event "Z" in experimental group : 12 in 25 people Experimental Event Rate : 12/25

Another worked example is as follows:

	Example 1: risk reduction			Example 2: risk increase
	Experimental group (E)	Control group (C)	Total	(E)	(C)
Events (E)	EE = 15	CE = 100	115	EE = 75	CE = 100
Non-events (N)	EN = 135	CN = 150	285	EN = 75	CN = 150
Total subjects (S)	ES = EE + EN = 150	CS = CE + CN = 250	400	ES = 150	CS = 250
Event rate (ER)	EER = EE / ES = 0.1, or 10%	CER = CE / CS = 0.4, or 40%	N/A	EER = 0.5 (50%)	CER = 0.4 (40%)

Equation	Variable	Abbr.	Example 1	Example 2
CER − EER	< 0: absolute risk reduction	ARR	(−)0.3, or (−)30%	N/A
	> 0: absolute risk increase	ARI	N/A	0.1, or 10%
(CER − EER) / CER	< 0: relative risk reduction	RRR	(−)0.75, or (−)75%	N/A
	> 0: relative risk increase	RRI	N/A	0.25, or 25%
1 / (CER − EER)	< 0: number needed to treat	NNT	(−)3.33	N/A
	> 0: number needed to harm	NNH	N/A	10
EER / CER	relative risk	RR	0.25	1.25
(EE / EN) / (CE / CN)	odds ratio	OR	0.167	1.5
EER − CER	attributable risk	AR	(−)0.30, or (−)30%	0.1, or 10%
(RR − 1) / RR	attributable risk percent	ARP	N/A	20%
1 − RR (or 1 − OR)	preventive fraction	PF	0.75, or 75%	N/A

See also

• Experimental event rate
• Absolute risk reduction
• Relative risk reduction
• Number needed to treat

References

1. ^ http://www.medicine.ox.ac.uk/bandolier/booth/glossary/CER.html

This statistics-related article is a stub. You can help Wikipedia by expanding it.v · Categories: Biostatistics Epidemiology Medical statistics Statistical ratios Statistics stubs Wikimedia Foundation. 2010. Игры ⚽ Нужно решить контрольную? Control Data Institute Control flow diagram Look at other dictionaries: Control rod — PWR control rod assembly, above fuel element A control rod is a rod made of chemical elements capable of absorbing many neutrons without fissioning themselves. They are used in nuclear reactors to control the rate of fission of uranium and… …   Wikipedia Control line — Brodak Control Line Aerobatic Strega in flight Control line (also called U Control ) is a simple and light way of controlling a flying model aircraft. The aircraft is connected to the operator by a pair of lines, attached to a handle, that work… …   Wikipedia Control (management) — Controlling is one of the managerial functions like planning, organizing, staffing and directing. It is an important function because it helps to check the errors and to take the corrective action so that deviation from standards are minimized… …   Wikipedia Control of the National Grid (UK) — The National Grid (UK) is the high voltage electric power transmission network in Great Britain, connecting power stations and major substations to ensure that electricity generated anywhere in Great Britain can be used to satisfy demand… …   Wikipedia Control of the National Grid — The National Grid is the high voltage electric power transmission network in Great Britain, connecting power stations and major substations, and has a synchronized organization such that electricity generated anywhere in Great Britain can be used …   Wikipedia Taxonomy of congestion control — refers to grouping congestion control algorithms according to their characteristics.Example classificationThe following is one possible classification according to the following properties: #The type and amount of feedback received from the… …   Wikipedia List of Control Panel applets — The applets listed below are components of the Microsoft Windows control panel, which allows users to define a range of settings for their computer, monitor the status of devices such as printers and modems, and set up new hardware, programs and… …   Wikipedia Permian–Triassic extinction event — …   Wikipedia Air traffic control — For the Canadian musical group, see Air Traffic Control (band). Airport Traffic Control Towers (ATCTs) at Amsterdam s Schiphol Airport, the Netherlands …   Wikipedia Technique for Human Error Rate Prediction — (THERP) is a technique used in the field of Human reliability Assessment (HRA), for the purposes of evaluating the probability of a human error occurring throughout the completion of a specific task. From such analyses measures can then be taken… …   Wikipedia 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”