# confidence interval

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## interval

[in´ter-val]the space between two objects or parts; the lapse of time between two events.

**AA interval**the interval between two consecutive atrial stimuli.

**atrioventricular interval**(

**AV interval**)

**1.**P–R interval.

**2.**in dual chamber pacing, the length of time between the sensed or paced atrial event and the next sensed or paced ventricular event, measured in milliseconds; called also atrioventricular or AV delay.

**cardioarterial interval**the time between the apical beat and arterial pulsation.

**confidence interval**an estimated statistical interval for a parameter, giving a range of values that may contain the parameter and the degree of confidence that it is in fact there.

**coupling interval**the distance between two linked events in the cardiac cycle.

**His-ventricular (H-V) interval**an interval of the electrogram of the bundle of His, measured from the earliest onset of the His potential to the onset of ventricular activation as recorded on eight of the intracardiac bipolar His bundle leads or any of the multiple surface ECG leads; it reflects conduction time through the His-Purkinje system.

**lucid interval**

**1.**a brief period of remission of symptoms in a psychosis.

**PA interval**the interval from the onset of the P wave on the standard electrocardiogram (or from the atrial deflection on the high right atrial ECG) to the A wave on the His bundle ECG; it represents intra-atrial conduction time.

**postsphygmic interval**the short period (0.08 second) of ventricular diastole, after the sphygmic period, and lasting until the atrioventricular valves open.

**P–R interval**in electrocardiography, the time between the onset of the P wave (atrial activity) and the QRS complex (ventricular activity).

**presphygmic interval**the first phase of ventricular systole, being the period (0.04–0.06 second) immediately after closure of the atrioventricular valves and lasting until the semilunar valves open.

**QRST interval**(

**Q–T interval**) in the electrocardiogram, the length of time between ventricular depolarization (the Q wave) and repolarization (the T wave); it begins with the onset of the QRS complex and ends with the end of the T wave.

**VA interval**[

*v*entricular-

*a*trial interval] the interval between a ventricular stimulus and the succeeding atrial stimulus; it is equal to the AA interval minus the atrioventricular interval.

## con·fi·dence in·ter·val (CI),

a range of values for a variable of interest, constructed so that this range has a specified probability of including the true value of the variable.

## confidence interval

Etymology: L,

*confidere,*to rely on; L,*intervallum,*area within rampartsa type of statistical interval estimate for an unknown parameter: a range of values believed to contain the parameter, with a predetermined degree of confidence. Its endpoints are the

**confidence limits,**and it has a stated probability**(confidence coefficient)**of containing the parameter.## confidence interval

A measure of the precision of an estimated value, which corresponds to a range of values consistent with the data that have a high probability (± 95%) of encompassing the "true" value. The confidence interval is expressed in the same units as the estimate. Wider confidence intervals indicate lower precision; narrower intervals indicate greater precision.## confidence interval

Statistics A range of values for a variable of interest–eg, a rate, constructed so that the range has a specified probability of including the true value of the variable. See Confidence limits.## con·fi·dence in·ter·val

**(CI)**(konfi-dĕns in'tĕr-văl)

Range of values for a variable of interest, constructed so that this range has a specified probability of including the true value of the variable.

## confidence interval (CI)

A statistical term that quantifies uncertainty. In a clinical trial, the 95% confidence interval (the interval usually employed) for any relevant variable is the range of values within which we can be 95% sure that the true value lies for the entire population of people from which those patients participating in the trial are taken. The greater the number of patients on which the confidence interval is based the narrower it becomes.## confidence interval,

## confidence

degree of assurance.

**confidence interval**

a range of values about a sample statistic that has a specified probability of including the true value of the statistic.

**confidence level**

1 minus the type 1 error; the probability that the trial under consideration will show no significant difference when there is in fact no significant difference between the treatments.

**confidence limits**

the highest and lowest values in a confidence interval.

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