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Topic: Level of measurement

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	Measurement
		Nominal level measurement is used to put objects with similar characteristics on the property or trait being evaluated into the same bin.
		The interval level measure is met to convey that the difference between any two adjacent measures is constant; it is the same everywhere on the scale.
		Ratio level measures have a zero point that means none of the trait is present; interval level measures do not have a zero point with this characteristic.
	www.ed.uab.edu /epr608/measurem.htm (567 words)

	Frequently Asked Questions About Level of Measurement
		Measurement of some attribute of a set of things is the process of assigning numbers or other symbols to the things in such a way that relationships of the numbers or symbols reflect relationships of the attribute being measured.
		As a measure of amount of reward, the number of pellets could only be justified by some very strong assumptions about the nature of rewards; the measurement level would depend on the precise nature of those assumptions.
		Measurement level is of greatest importance in situations where the meaning of the null hypothesis depends on measurement assumptions.
	www.people.vcu.edu /~pdattalo/702SuppRead/FAQs_measure.html (5638 words)

	Level of measurement - Wikipedia, the free encyclopedia
		The level of measurement of a variable in mathematics and statistics is a classification that was proposed in order to describe the nature of information contained within numbers assigned to objects and, therefore, within the variable.
		According to the classification scheme, in statistics the kinds of descriptive statistics and significance tests that are appropriate depend on the level of measurement of the variables concerned.
		Variables measured at the interval level are called interval variables, or sometimes scaled variables, though the latter usage is not obvious and is not recommended.
	en.wikipedia.org /wiki/Level_of_measurement (1186 words)

	Levels of Measurement (Site not responding. Last check: 2007-09-11)
		The level of measurement refers to the relationship among the values that are assigned to the attributes for a variable.
		At lower levels of measurement, assumptions tend to be less restrictive and data analyses tend to be less sensitive.
		In general, it is desirable to have a higher level of measurement (e.g., interval or ratio) rather than a lower one (nominal or ordinal).
	www.socialresearchmethods.net /kb/measlevl.htm (659 words)

	POWERMUTT: Levels of Measurement
		Level of measurement is important because the higher the level of measurement of a variable (note that "level of measurement" is itself an ordinal measure) the more powerful are the statistical techniques that can be used to analyze it.
		Sometimes the question of level of measurement hinges on the precise nature of the measure itself.
		Remember, however, that the level of measurement of some variables may depend on how the variable is used. Also, when using datasets other than those provided with POWERMUTT, do not assume without checking that the author has bothered to verify each variable's level of measurement.
	www.csupomona.edu /~jlkorey/POWERMUTT/Topics/levels_of_measurement.html (1681 words)

	A practical overview of Level Continuous Measurement Technologies
		A DP is used to transmit the head pressure that the diaphragm senses due to the height of the material in the vessel multiplied by a density variable.
		Level is inferred from the time of flight (transmission to reception) of the microwave signal.
		As the level rise’s and material begins to cover the sensing element the capacitance within the circuit between the probe and the media (conductive applications) or the probe and the vessel wall (insulating applications) increases.
	www.iceweb.com.au /Technical/LevelTechnologies.html (3083 words)

	Measurement Scales (1 of 6) (Site not responding. Last check: 2007-09-11)
		Measurement is the assignment of numbers to objects or events in a systematic fashion.
		Four levels of measurement scales are commonly distinguished: nominal, ordinal, interval, and ratio.
		One position is that data must be measured on an interval or a ratio scale for the computation of means and other statistics to be valid.
	davidmlane.com /hyperstat/A30028.html (168 words)

	Level of Measurement Refresher
		Nominal Level of Measurement At the nominal level of measurement, numbers or other symbols are assigned to a set of categories for the purpose of naming, labeling, or classifying the observations.
		Interval/Ratio Level of Measurement If the categories (or values) of a variable can be rank-ordered, and if the measurements for all the cases are expressed in the same units, then an interval-ratio level of measurement has been achieved.
		In some discussions of levels of measurement you will see a distinction made between interval-ratio variables that have a natural zero point (where zero means the absence of the property) and those variables that have zero as an arbitrary point.
	courses.csusm.edu /soc201kb/levelofmeasurementrefresher.htm (450 words)

	A Level Measurement Orientation
		From this example, we can see that level measurement is more complex than simply the determination of the presence or absence of a fluid at a particular elevation.
		When the level to be measured is a solid, slurry, foam, or the interface between two liquid layers, it is advisable to consult not only Table 4, but other recommendations, such as Table 5.
		Measuring the level of molten glass or metals is another special application.
	www.omega.com /literature/transactions/volume4/T9904-11-LEVEL.html (1269 words)

	Level Measurement \| Lasers come to level measurement \| Control Global
		Similarly, laser-level measurement sensors emit a laser beam towards the material, and measure the remnants of the beam reflected from the material.
		For example, the level of flour is difficult to measure using laser level technology because it contains fine particles that reflect light and contain an electric charge that causes light to be obstructed, reflected, and collect on the sensor.
		The laser-level transmitter is mounted on the far side of the bin, and measures the horizontal level in the bin.
	www.controlglobal.com /articles/2006/018.html (1632 words)

	Introduction to Level Measurement Methods
		Measurement of liquids as with the Dipstick where smaller changes in level are required to be measured.
		Measuring the differential pressure between the surface of the liquid and the bottom of the liquid can be used to provide a level.
		Level measurement of liquids (including corrosive and high temperatures) can be achieved accurately with the capacitance gauge.
	www.searcheng.co.uk /articles/level/index.htm (666 words)

	UCEL: Showroom
		There are 4 levels of measurement and it is important to know what level of measurement you are working with as this partly determines the arithmetic and statistical operations you can carry out on them.
		The four levels of measurement in ascending order of precision are: nominal, ordinal, interval and ratio.
		As we go on to describe and give examples of each of these levels you'll see that the numbers used to describe nominal data are simply used to classify data whereas the numbers describing interval or ratio measurements are much more precise and represent actual amounts.
	www.ucel.ac.uk /showroom/levels_of_measurement/Default.html (129 words)

	Level Measurement Methods - Pressure Method (Site not responding. Last check: 2007-09-11)
		The fuller the tank the greater the level in the tank.
		The upper pressure sensor is used to detect the pressure at the surface of the liquid and is used to compensate for changes in the vessel pressure.
		By measuring the pressure at the surface of the liquid pressure changes in the vessel can be detected and the measured pressure compensated to give an accurate record.
	www.searcheng.co.uk /articles/level/pressure.htm (300 words)

	Industrial Lasers for Level Control, High Accuracy, Reasonable Cost
		To accurately measure distance, the time required for light to make a round trip between the measuring device and the object is measured.
		The simplest, conceptually, is the time-of-flight approach that measures the elapsed time between when a short pulse of light leaves the instrument and when the returning reflected or scattered pulse is detected.
		Conceptually more complex, but electronically simpler, is to measure the phase of a modulated light beam when it leaves the instrument, and then compare that phase to the phase of the return light.
	www.hitechtech.com /laser.htm (338 words)

	Levels of Measurement (Site not responding. Last check: 2007-09-11)
		Level of measurement refers to the inherent nature of a variable and the values it admits based upon the conditions attached to, or the relations obtaining among these values.
		The lowest of the levels of measurement entails just the distinction (same or different) relation, while the highest requires the distinction, order, and distance relations, and a zero value.
		INTERVAL DATA: A level of measurement for which data possess both the distinction and the order relations, but also a distance or metric relation; however, for which there is no inherent zero value.
	web.uvic.ca /~ling48x/ling483/levels.html (338 words)

	Level transmitters - measurement of liquids and bulk solids
		An Ultrasonic level transmitter will use an acoustic pulse which is emitted from the transducer towards the surface to be measured.
		Level measurement is necessary in most wastewater, water and process plants economical and rugged ultrasonic level transmitter,
		Ultrasonic level transmitters use an acoustic pulse which is emitted from the transducer towards the surface to be measured.
	www.ultrasonic-level-transmitters.com /links.html (1420 words)

	Radar Level Measurement
		The reflected radar signal is delayed in proportion to the distance to the level surface.
		Where ultrasonic sensors transmit its pulses and calculate the level based on the speed of sound, pulsed radar also transmits it pulses towards its liquid level target at the speed of light.
		Consequently conditions that affect the speed of sound used in ultrasonic level measurement such as variations in pressure, vacuum, temperature do not affect the speed of light used in radar level measurement.
	www.cancoppas.com /radar_level_measurement.html (396 words)

	Continuous level measurement
		Today, level measurement technology is the basis of process measurement and control in the chemical and petrochemical industries, environmental technology and other process-oriented industries.
		Measuring sensors detect the current filling level of the medium at all times.
		Continuous measurements can be made up to Zone 0 in the hazardous area, by choosing the appropriate devices with ATEX 100 approval.
	www.pepperl-fuchs.com /pa/levcon/cont-lev-con/default_e.html (204 words)

	Levels of Measurement (Site not responding. Last check: 2007-09-11)
		Essentially, a measure's level of measurement is determined by the nature of it's categories.
		Level of measurement has to do with the nature of those distinctions.
		Determining the level of measurement of a given variable is a straightforward process of identifying certain characteristics of it's categories.
	www.fau.edu /divdept/polsci/people/3936/levels.html (374 words)

	ENDRESS+Hauser - Updated level measurement handbook
		The handbook opens with an explanation of the terminology, symbols and principles of level measurement.
		This is followed by a look at capacitive and conductive level detection and various probes used for measurement.
		Separate chapters are devoted to level detection using vibrating switches; electromechanical level measurement; level measurement using hydrostatic pressure; ultrasonic level switching and measurement; microwave level measurement; and nucleonic level detection and measurement.
	www.ferret.com.au /articles/d8/0c0407d8.asp (276 words)

	Level Measurement and Control Solutions Capability from Mobrey
		Accurate liquid level and contents data is vital in the process industries where inventories, batching and process efficiency are critical measurements.
		Reliable liquid level detection for high and low alarm or pump control is essential in industry.
		It is important to select a level switch to suit the application, which is why Mobrey offers a choice of technologies and products, including the original Mobrey float operated liquid level switches, vibrating fork liquid level switches and ultrasonic gap sensors and switches.
	www.mobrey.com /products/level/index.php (233 words)

	level measurement
		Ultrascan S Ultrasonic Level Transmitter, for liquid level, solids level and open channel flow, non contact measurement, ULTRASCAN S has a range of up to 15 m (49.21 ft) and an accuracy of 0.25% within that range.
		Ultrascan M Ultrasonic Level Transmitter, easy to install, non contact level measurement, ULTRASCAN M is available with ranges up to 40 metres and an accuracy of 0.25% within that range.
		Shuttle Ultrasonic Level Transmitter, easy to install, non contact level measurement, 10cm to 15m measurement range, 1mm accuracy, digital display, analogue 4-20mA and 2 relay outputs.
	www.omniinstruments.net /level/level.html (243 words)

	Levels of Measurement (Site not responding. Last check: 2007-09-11)
		Though the concept of levels has its problems (see Velleman and Wilkinson, 1993), it is a good way to begin thinking about the data.
		Traditional texts say that levels of measurement include nominal, ordinal, interval and continuous (or ratio).
		So, the idea of "levels of measurement" comes from an understanding in the statistical community of many who have come to see names as a "lower," less powerful level of measurement than numbers.
	colfa.utsa.edu /Sociology/masters/levels.htm (570 words)

	EchoSpan, MiniMe Ultrasonic Level Transmitters - Non-contact Level Measurement
		The EchoSpan is a general purpose two-wire ultrasonic transmitter provides non-contact level measurement up to 32' or 10m, and is ideally suited for challenging ultrapure, corrosive or waste liquids.
		The general purpose two-wire ultrasonic transmitter provides non-contact level measurement up to 40' or 12.2m, and is ideally suited for challenging corrosive, coating or waste liquids.
		The general purpose two-wire ultrasonic transmitter provides non-contact level measurement up to 4' or 1.2m, and is ideally suited for challenging ultrapure, corrosive, slurry or waste liquids.
	www.flowlineoptions.com /level/liquid-level-transmitters.html (380 words)

	Level Ultrasonic Measurement, VEGA Measurement Indicators
		You can use ultrasonic level transmitters to measure most liquids or solids for level indication in storage or process applications, at temperatures up to 150 degrees C and pressures up to 3 bar.
		VEGASON ultrasonic level sensors can be used to measure flow too; built in flow curves for flumes, weirs and V notches provide direct output of flow, without any need for additional signal conditioners.
		The elapsed time period between transmission and reception of the signal - at the speed of sound - is measured and calculated as a distance and computed into level or volume.
	www.vegacontrols.co.uk /vegason_ultrasonic_index.asp (526 words)

	Water Level Measurement
		It can be used for measuring soil conductivity, monitoring the height of water in rivers, or measuring flow rates etc. The data is downloaded directly onto a PC without the need of further equipment.
		The probe senses the water level by detecting the change in internal reflection of a light source which is encapsulated in the probe tip.
		Dip-well measuring probe works in a similar manner to the dip-well probe as described above but has a rigid probe which has a scale attached to it so that the water level can be read off directly.
	www.chambers-electronics.com /water_level_and_flow_measurement.htm (229 words)

	Levels of Measurement
		The least precise level of measurement is the nominal level.
		The highest level of measurement is the ratio level.
		Thus, it is an ordinal-level measure of education.
	chss.montclair.edu /sociology/statbooklevels.htm (1969 words)

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