Scale is a way to represent real-world objects on a drawing or model. This helps artists see how large or small an object is and to make it more recognizable. It also helps architects, machine-makers and designers create blueprints.

There are many advances in scale creation. However, few have a clear focus on construct validity and readability. This article presents five such advances.

## Interval scales

Interval scales are a type of measurement scale that has order and distance between values but does not have a true zero point. Interval scales are more precise than nominal or ordinal scales and can be used for statistical analysis.

Most of the time, you will see interval scale questions in your surveys such as a five-point Likert Scale question that asks how satisfied or dissatisfied you are with a product/service. Temperature is also measured on an interval scale, whether in Celsius or Fahrenheit. Other examples include standardized tests and psychological inventories. However, you should not confuse an interval scale with a ratio scale. A ratio scale has a meaningful zero point (zero energy, for instance) while an interval scale does not. These differences are important in understanding how to analyze data.

## Ratio scales

In market research, marketers often make use of four types of data measurement scales – Nominal, Ordinal, Interval, and Ratio. The ratio scale is the most useful for analyzing data, since it contains all the features of interval and ordinal scales and has a true zero point. This non-arbitrary zero allows for easier calculation of the value behind attributes collected in a survey.

In addition, ratio scales can be used to calculate statistical parameters like mean, median, and mode, which are helpful for identifying trends in the data. Furthermore, they can be used to determine correlation between multiple variables using a contingency table. This is particularly important in cases where there is no clear relationship between the variables. For example, a ratio variable can be used to measure the time an individual spends playing video games.

## Continuum scales

Continuum scales are used to measure the size of a physical quantity. These scales are often used in size measurements in physics, chemistry, and biology. A number on a continuum scale can only be determined by comparison with another value on the same scale. For example, a cylinder’s length can only be measured by comparing it to the diameter of an adjacent cylinder. This method is useful for comparing very large numbers that would otherwise be difficult to distinguish.

The mental health continuum is a fluid scale that everyone lives and moves on, based on various challenges. It consists of 3 items that reflect hedonic well-being, 11 items that measure psychological well-being, and 5 that measure social well-being (when combined, this reflects eudemonic well-being). Respondents indicate the frequency with which they experience these symptoms of positive mental health.

## Likert scales

Likert scales are a popular and convenient way to collect customer feedback. They offer a more diverse range of options than a simple yes/no question, and they increase the response rate by allowing respondents to indicate their levels of satisfaction or dissatisfaction. However, it is important to understand how to interpret and analyze Likert-scaled data properly. Deciding which descriptive statistics and inferential statistics may legitimately be used to describe and analyze data from a Likert question is a challenging issue. Most researchers treat Likert-derived data as ordinal, meaning that the distances between response categories cannot be presumed to be equal.

Some researchers also use parametric statistical tests on ordinal data, such as analysis of variance (ANOVA) and Pearson’s product-moment correlation. However, these methods require arithmetic manipulation of the data and can be subject to social desirability bias.

## Bipolar scales

Many surveys use rating scales to measure attitudes, behaviors and other phenomena that have a dimensional quality. These scales can be bipolar or unipolar. A bipolar scale contrasts opposites, while a unipolar scale focuses on one attribute. For example, a bipolar Likert scale asks respondents to rate whether a statement is boring or interesting. Respondents have to balance two polar opposite attributes, which requires more cognitive effort than a unipolar scale.

Using a bipolar scale when you could have used a unipolar one can confuse your respondents and skew your results. In addition, it may lead to a “topping effect”, in which respondents give too many high ratings. This is particularly true for a bipolar question with a large range of options, such as a five-point scale.