Oh, all the wonderful data youu2019ll collect! Data is all around us, you just need to know where to look. If you wanted to, you could download a dataset online for free, and play around with thousands of data points. You might also want to collect and categorize your data for analysis.

Most scientific experiments start with data collection. Understanding the class of data you are collecting is an important step in designing your study. Here, weu2019ll summarize the different types of data and define them for you, with examples.

## u00a0

## Nominal

The nominal class of data possesses qualitative aspects. It could be something like hair color, favorite book, or hometown. Remember, if youu2019re collecting nominal information, you could be at risk of introducing bias. Make sure you donu2019t use leading questions during your data collection process.

You canu2019t use the same quantitative methods with nominal data. However, youu2019ll be able to calculate the mean and mode. You will still be able to use these variables in comparisons between two different groups.

## u00a0

## Ordinal

How confident are you that you could win a wrestling match with a gorilla? You could say:

1 – Very confident

2 – Confident

3 – Unsure

4 – Not Confident

5 – This is not going to end up well!

u00a0Sure, there are some numbers involved but the numbers themselves donu2019t carry any value. However, the numbers do have some intrinsic order to rank confidence. We just donu2019t know the size of the difference between 1 and 2 or 3 and 5. But we do know that 1 is more confident than 2, and 5 is significantly less confident than 3. You can determine the mode and median of this data to give you an idea of averages.

## u00a0

## Interval

The interval scale is as self-explanatory as they come. It features measurements that tell us both the order and exact difference between variables. Think of measuring temperature in Ireland. You can use the Celsius scale to track how warm it is outside.u00a0

You know that 10 degrees Celsius is smaller than 20 degrees Celsius. You also know that the difference between 10 and 20 degrees Celsius is the same as the difference between 30 and 20 degrees Celsius. But where these measurements fail is giving us ratios, providing meaning for a value of zero. This means that we canu2019t say that 20 degrees Celsius is twice as hot as 10 degrees Celsius.

This is the first type of variable that weu2019ve encountered where you can calculate mean, median, and mode.

## u00a0

## Ratio

Height, weight, and time are classical ratio data measures. Not only is it an ordered numerical scale where we know the magnitude of differences, but we also have a true zero. Having a true zero lets us compare data using ratios as well as opening up a whole array of inferential statistics we can perform during further analyses.

## u00a0

## Takeaway

If you want to design a good experiment, youu2019ll need to determine what kind of data youu2019ll collect. Each class of data has unique type features and nuances, as well as weaknesses. The data you collect will also determine how you measure central tendency and your later statistical analyses.