| average |
Also known as the mean. The approximate value of each number in a set of numbers. The average is found by dividing the sum of a set of numbers by the number of members in the group. |
| bell-shaped curve |
A common type of histogram characterized by a high center, tapered sides, and bell-flared edges. A bell-shaped curve reflects conditions that exhibit natural variation. |
| data |
A collection of numbers or facts that is used as a basis for making conclusions. Data is collected by manufacturers about their facilities. |
| fraction |
A math expression with two numbers placed above and below a division line. A fraction indicates the number of divisions or portions and the size of each division or portion. |
| Gaussian distribution |
A common type of histogram characterized by a high center, tapered sides, and bell-flared edges. Gaussian distribution is another name for a bell-shaped curve. |
| histogram |
A visual graph that shows the frequency of a range of variables. Histograms are typically used to measure distribution patterns. |
| horizontal scale |
The portion of a histogram that lists the range of variables. The horizontal scale runs across the bottom of the histogram and is usually read from left to right. |
| mean |
Also known as the average. The approximate value of each number in a set of numbers. The average is found by dividing the sum of a set of numbers by the number of members in the group. |
| median |
The value of a numerical set that equally divides the number of values that are larger and smaller. For example, in a set containing nine numbers, the median would be the fifth number. |
| mode |
The value within a numerical set that appears with the greatest frequency. The mode is the number that repeats the most within a set. |
| natural variation |
Variation resulting from random, normal differences that are expected and inevitable. Slight differences in raw materials are one cause of natural variation. |
| normal distribution curve |
A common type of histogram characterized by a high center, tapered sides, and bell-flared edges. Normal distribution curve is another name for a bell-shaped curve. |
| percentage |
An amount expressing what portion of a whole is present. Percentages are similar to fractions or decimals expressed in hundredths. |
| population mean |
The mean of a numerical set that includes all the numbers within the entire group. The population mean is helpful in making informed decisions based on an entire group. |
| predictions |
A forecast of coming events. Predictions allow manufacturers to make informed decisions about their facilities, parts, purchasing and other various areas. |
| probability |
The likelihood that a particular event will happen in the future. Probability can be expressed as a fraction, ratio, or percentage. |
| process |
The series of activities that leads to a desired result. There are many processes in manufacturing, and they often lead to production of a part. |
| random sampling |
The process of collecting and analyzing only a small representative portion of a larger group. Random sampling dictates that each item must have the same likelihood of being selected. |
| range |
The difference between the smallest and the largest values within a numerical set. Range shows the amount of variation in a set. |
| ratio |
A numerical expression representing a part of a larger whole or proportion. A ratio consists of two numbers separated by a colon. |
| sample |
A representative part from a larger group. A larger sample increases accuracy. |
| sample mean |
A mean of a numerical set that includes an average of only a portion of the numbers within a group. A sample mean is an approximation of the actual mean. |
| scrap |
Any material not used to create the final part. During most machining operations, scrap appears in the form of chips. |
| standard deviation |
A number representing the degree of variation within a numerical set. Calculating the standard deviation of a numerical set shows the average amount of deviation. |
| statistics |
The science of collecting, summarizing, and analyzing numerical information, which is often used to make good decisions with confidence in an otherwise uncertain environment. |
| tolerances |
An unwanted but acceptable deviation from a given dimension. Checking for accurate part tolerance is done after a successful first part run. |
| unnatural variation |
Variation resulting from one or more sources that involve a fundamental change in a process. Unnatural variation is undesirable. |
| variation |
Any difference that exists between two or more related things. |
| variation |
Any difference that exists between two or more related things. Variation is an unavoidable occurrence. |
| vertical scale |
The portion of a histogram that indicates the frequency of each variable. The vertical scale runs along the side of a histogram from bottom to top. |