normal curve


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Related to normal curve: standard deviation

normal curve

a frequency distribution which has a bell-shaped symmetrical pattern where it is possible to calculate the height of the curve (the frequency) corresponding to any given numerical value.

Normal curves are used in statistical QUALITY CONTROL to establish the limits of variation in the size or other characteristic of a product which is to be regarded as acceptable in SAMPLES of a product being tested. For example, if a component is intended to measure an average of 100 mm across and the standard deviation is 2 mm, then the testers would expect 95% of a sample of components to measure between 96 mm and 104 mm across, and 99% of the sample to measure between 94 mm and 106 mm across. If the latter range of sizes was felt be acceptable in terms of the technical performance of the product, then this confidence interval would lead to the whole batch of components being rejected if more than 1% of sample components were larger or smaller than these broad limits. By contrast, if a tougher criterion was imposed and only components measuring 96 mm to 104 mm across were to be regarded as technically acceptable, then 95% of sample components would be acceptable. and if more than 5% of the sample were larger or smaller than these size limits then the whole batch of components would be rejected.

References in periodicals archive ?
This essay provides a personal reflection on the past, present and future of the modem integration movement, There three lenses provide focus for describing five topics deemed to be contral to the integrative enterprise; 1) normal curves 2) invisible things.
3) Speed distributions of different vehicle types observed on the road section were fitted for a normal curve, except the speed distributions for motorized 2-wheeler that were modelled as lognormal distribution.
Updates to the Toolkit include a new drag-and-drop feature that allows users to focus on specific data points along the Normal Curve, a lap time component that adds functionality to the Stopwatch feature, and a Compliancy Calculator that enables the user to manage holidays, important dates, and other user-input special days.
The performance level category (below basic, basic, proficient, and advanced) and the Normal Curve Equivalent (NCE) from the Dakota STEP were collected for each student by grade level available.
The distribution, your old friend the normal curve, slopes downward steadily on each side of the 48 percent.
Assuming a standard normal curve, the result can be interpreted that the average student's academic gain would improve from the 50th percentile to approximately the 60th percentile by implementing field trips.
But again, that all goes back to the natural development process for a young player, and the fact Loney clearly is ahead of the normal curve.
But the low-dose end of the cumulative normal curve is linear.
Laplace discovered that the means are distributed approximately according to the normal curve and the Central Limit Theorem is sometimes known as the "normal law of random errors.
2) Those acquainted with such statistics, or earthquakes and the Richter scale, that is the maths of 'power laws', will recognize the normal curve, the trade-off that swings from top left to low right.
The scale scores and normal curve equivalents of the norm referenced component of the Tennessee Comprehensive Assessment Program (TCAP) were dependent variables.
These build on basic and advanced skills and competencies such as those identified by SCANS (1991), move toward capacity to perform and away from ranking by way of the normal curve, and reinforce capability as opposed to entitlement.