These formal academic nouns keep the plural from Greek or Latin, so the ending shifts instead of just adding -s. A criterion is a standard you judge or decide something by, and its plural is criteria. A phenomenon is an observable fact or event that can be studied, and its plural is phenomena. An analysis is a careful, detailed examination of something, and its plural is analyses (say "-seez"). Because these plurals don't look like plurals, learners often add an extra -s, which sounds off to an examiner.
Greek and Latin plurals
criteria /kraɪˈtɪriə/ — Each applicant must meet all four criteria before the panel reviews the file.
phenomena /fəˈnɑmənə/ — The study compares two phenomena that rarely appear together.
analyses /əˈnæləˌsiz/ — The three separate analyses all pointed to the same conclusion.
Not ""Each candidate must meet specific criterias." (double plural: criteria is already plural)" — say ""Each candidate must meet specific criteria."". Criteria is already the plural; the singular is criterion. Never add -s to make 'criterias'.
Try it: Which sentence uses the academic plural correctly? (Scientists are studying these unusual phenomena. / Scientists are studying these unusual phenomenons. / Scientists are studying these unusual phenomenas.) Answer: Scientists are studying these unusual phenomena. — 'Phenomena' is the correct Greek plural of 'phenomenon' (an observable fact or event). 'Phenomenons' wrongly treats the singular as a regular noun, and 'phenomenas' adds -s to a form that is already plural, so it double-marks the plural.
Abstract nouns for ideas
Formal writing leans on abstract nouns to name ideas precisely. Significance means the importance or deeper meaning of something. An implication is a consequence or result that follows from something. A perspective is a viewpoint or angle you look at a question from. They often sit in fixed pairings, such as serious implications or from multiple perspectives. All three are neutral-to-formal in register and fit academic writing well.
significance /sɪɡˈnɪfɪkəns/ — The authors overstate the significance of a fairly small change.
implication /ˌɪmplɪˈkeɪʃən/ — Raising the fee has an implication for lower-income students.
perspective /pərˈspɛktɪv/ — Reading the letters gives us a perspective the official records leave out.
Not ""We need to examine this from multiple prospect." (prospect means a future possibility, not a viewpoint)" — say ""We need to examine this from multiple perspectives."". A perspective is a viewpoint you argue from; a 'prospect' is a future possibility. Keep them apart, and use the plural for several viewpoints.
Try it: Choose the noun that fits: "The report warns of serious ___ for public health if the trend continues." (implications / significances / perspectives) Answer: implications — 'Implications' names the consequences that follow from the trend, which is what 'serious ___ for public health' calls for. 'Significances' means importance and isn't used this way (it rarely takes a plural), and 'perspectives' means viewpoints, not consequences.
Try it: Which sentence uses the abstract noun correctly? (The significance of this research is clear. / The significancy of this research is clear. / The significant of this research is clear.) Answer: The significance of this research is clear. — 'Significance' is the noun meaning importance. 'Significancy' is archaic and not used in modern English, and 'significant' is the adjective, so it can't sit after 'the' as the head noun here.
Methodology and framework
Two nouns describe how a study was set up, and they are easy to swap by mistake. A methodology is the system of methods a study uses to gather and analyze its data, so it answers what the researchers actually did. A framework is the set of ideas that organizes the thinking, so it answers how they make sense of what they found. A paper describes its methodology in the methods section and states its framework when it explains its reasoning.
methodology /ˌmɛθəˈdɑlədʒi/ — The paper devotes six pages to its methodology before reporting any results.
framework /ˈfreɪmwɜrk/ — She borrows a theoretical framework from economics to explain the voting data.
Not ""We interviewed 40 people using a theoretical framework of open questions." (that describes the procedure, not the ideas)" — say ""We interviewed 40 people using a methodology of open questions."". A methodology is the procedure you followed. A framework is the set of ideas you interpret the results with. If the sentence describes a step someone carried out, the word is methodology.
Try it: Choose the noun that fits: "The study borrows a theoretical ___ from linguistics to organize its analysis." (framework / methodology / correlation) Answer: framework — If you chose methodology, that names the procedure a study carries out, and nothing here describes a procedure. The sentence borrows ideas from another field to organize the thinking, and the set of ideas you reason with is a framework. A correlation is a measured relationship between two variables.
Assumption
An assumption is something researchers take as true without testing it, so it sits underneath the work rather than coming out of it. The fixed phrase is make an assumption, and a study is often said to rest on an assumption. Note the spelling: the noun from assume is assumption, with -mption.
assumption /əˈsʌmpʃən/ — The model rests on the assumption that prices adjust immediately.
Not ""After analyzing the data, the team reached the assumption that air quality matters." (that is what they proved, not what they took for granted)" — say ""Before collecting any data, the team made the assumption that air quality matters."". An assumption is what you accept before the evidence. What you arrive at after the evidence is a conclusion. The verbs go with them: you make an assumption, you reach a conclusion.
Try it: Choose the noun that fits: "The whole model rests on one untested ___, namely that buyers always act rationally." (assumption / conclusion / framework) Answer: assumption — If you chose conclusion, that is what a study arrives at after weighing evidence, but this claim is described as untested and the model rests on it, so it comes first. Something accepted as true before the evidence is an assumption. A framework is the wider set of ideas, not a single claim.
What the study found
Two more nouns report results. A correlation is a measured relationship between two things that change together, so it can be strong or weak and positive or negative. Validity is whether a study really measures the thing it claims to measure. Note the warning that always travels with the first one: a correlation on its own never proves that one thing caused the other.
correlation /ˌkɔrəˈleɪʃən/ — There is a strong negative correlation between screen time and hours slept.
validity /vəˈlɪdəti/ — Reviewers questioned the validity of a test that measured confidence rather than skill.
Not ""The study found a strong negative comparison between pollution and test scores." (a comparison is not measured as positive or negative)" — say ""The study found a strong negative correlation between pollution and test scores."". Only a correlation takes strong/weak and positive/negative. A comparison sets two things side by side; it has no direction.
Try it: Choose the noun that fits: "Reviewers doubted the ___ of the test, since it measured confidence rather than ability." (validity / correlation / methodology) Answer: validity — Validity is whether a test measures what it claims to measure, which is exactly the doubt described. A correlation is a relationship between two variables, and a methodology is the system of methods used.