Systems of Measurement: there are two main systems of measurement in the world: the Metric (or decimal) system and the US standard system. In each system, there are different units for measuring things like volume and mass. What makes the US standard systems different from the Metric system?

Many variables studied by psychologists are straightforward and simple to measure. These include sex, age, height, weight, and birth order. You can often tell whether someone is male or female just by looking.

You can see that one way to look at variables is to divide them into four different categories ( nominal, ordinal, interval and ratio). These refer to the levels of measure associated with the variables. In everyday usage the convention is to then use the level of measure to refer to the kind of variable.

Top Common Tools to Measure Distance

• The Ruler.
• Measuring Tape.
• Measuring Wheel.
• Long Tape or Tape Reel.
• Laser Tape. Conclusion.
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Tape Measures

A simple opisometer consists of a toothed wheel of known circumference on a handle. The wheel is placed in contact with the curved line to be measured and run along its length. The instrument is most commonly used to measure the lengths of roads, rivers and other line features on maps.

Measurement tools make our lives better and safer, and they enhance the quality and quantity of life. Arguably, the ability to measure physical properties accurately has tremendous survival value that gives humans an adaptive, evolutionary advantage honed through many years of natural selection.

A good measuring instruments posses’ three qualities, which include: validity, reliability and usability. Validity – the extent to measure what it intends to measure. It has four types; the content, construct, concurrent and predictive. Usability of test means its practicability.

What are the Qualities of a Good Test?

• Isolated (unaffected by the presence, absence, or results of other tests)
• Automated.
• Quick to write.
• Quick to run.
• Unique (providing confidence not provided by other tests/uncorrelated. with other tests)

Validity: • Extent to which a scale produces consistent results (the effective ness) • Reliability: Getting the same result by repeating the measurement to over come the errors. Practicality: Measuring instrument can be judged in terms of economy(cost,time,resources etc).

Characteristics of a good measurement: Validity, Reliability, and Sensitivity – accuracy of the measuring instrument. 7. a. Stability of Measures • Ability of the measure to remain the same over time.

Validity refers to what characteristic the test measures and how well the test measures that characteristic.

• Validity tells you if the characteristic being measured by a test is related to job qualifications and requirements.
• Validity gives meaning to the test scores.

A good test should be highly reliable. This means that the test should give. similar results even though different testers administrate it, different. people scores in different forms of the test are given and the same person. takes that test at two or more different times.

The Four Scales of Measurement

• Nominal Scale. Nominal variables (also called categorical variables) can be placed into categories.
• Ordinal Scale. The ordinal scale contains things that you can place in order.
• Interval Scale. An interval scale has ordered numbers with meaningful divisions.
• Ratio Scale.