Criteria or criterion
There is some confusion about the use of the word criteria. Let’s clear it up by giving some information about the word. The Oxford Dictionary defines criterion as, “ a principle or standard by which something may be judged or decided”. Criteria is the plural form of the word criterion. The word criterion comes from the Greek word kriterion.
The confusion arises because some persons tend to use the plural form of the word criteria as singular. Here is an example of such usage. The main criteria for giving a loan is the ability of the borrower to repay. There is only one standard of judgement that is mentioned so the singular form criterion should be used. You should then take care when writing or speaking to use the correct form of the word whether singular or plural. To avoid confusion then remember to use criterion when you refer to only one “principle or standard” of judgement and use criteria when you refer to several standards.
Examples:
The performance of the divers was judged on four criteria.
Reliability was the major criterion used to select my new intern.
Is data singular or plural?
The usage of data is also an area for clarification. The word data is actually plural and its singular is datum. Sticking strictly to grammar rules we should treat data as plural.
The collected data indicate that the spider population is increasing.
However the usage of data has been changing. Over time the word data is increasingly being used as a singular noun.
The data I gathered from the survey is stored on my computer.
According to the English Oxford Living Dictionaries data is used as a plural in “specialised scientific fields” but is treated as a mass noun in “modern, non-scientific use”. A mass noun takes a singular verb.
According to the Oxford information on its usage data though plural in form is generally used with a singular verb.
The Merriam-Webster Dictionary recognises that data can be used as “a plural noun (like earnings) taking a plural verb and also as an abstract mass noun (like information) taking a singular verb. Merriam-Webster’s advice differs slightly from that of the English Oxford Living Dictionaries. While the English Oxford Living Dictionary indicates that data as plural is only used in the scientific field, Merriam- Webster does not confine the plural use to the scientific field.
I summarise and advise that you can use data as either plural or as singular. My further advice is to be consistent with the usage you choose to adopt in any one piece of writing.