Learn Hardcore German: Unsere Forschung vergleicht zwei Methoden und erklärt die Theorie dahinter. - Our research compares two methods and explains the theory behind them.

Forschung = feminine, singular, nominative
In the nominative singular feminine, unser takes the ending -e → unsere Forschung
Compare:
- unser Vater (masc., nom. sg.)
- unsere Mutter (fem., nom. sg.)
- unser Kind (neut., nom. sg.)
- unsere Kinder (plural, any gender, nom.)

Unserer would be used in other cases, e.g. genitive or dative feminine:

wegen unserer Forschung (genitive)
mit unserer Forschung (dative)

What gender and case is Forschung, and how can I tell?

Forschung is:

Gender: feminine
Number: singular
Case: nominative

You can tell:

The article/determiner: unsere indicates nominative feminine singular (see previous answer).
Function in the sentence: Unsere Forschung is the subject (the thing doing the comparing and explaining), and subjects are typically in the nominative case.
Lexical gender: in dictionaries, Forschung appears as die Forschung (f.).

Why is it vergleicht and not vergleichen?

vergleicht is the correctly conjugated form of the verb vergleichen in the 3rd person singular, present tense.

Infinitive: vergleichen (to compare)
Subject: unsere Forschung = 3rd person singular
Present tense endings:
- ich vergleiche
- du vergleichst
- er/sie/es vergleicht
- wir vergleichen
- ihr vergleicht
- sie/Sie vergleichen

Since the subject is unsere Forschung (it), you need vergleicht. vergleichen is used with wir, sie (they), or as an infinitive.

Why doesn’t Forschung become plural here, even though we compare two methods?

Forschung refers to the research project or body of research as a whole. It is a singular, abstract noun. The number two belongs to Methoden, not to Forschung.

Unsere Forschung (singular) = our research
zwei Methoden (plural) = two methods

So, there is one research project that compares two methods. If you wanted to talk about several research projects, you would say unsere Forschungen, but that’s much less common in everyday academic language.

Why is there no comma before und?

In this sentence, und connects two verbs that share the same subject (unsere Forschung) in a single main clause:

Unsere Forschung
- vergleicht zwei Methoden
- und erklärt die Theorie dahinter.

In German, you do not put a comma before und when it simply joins:

two parts of the predicate (two verbs with the same subject)
or two items in a list
or two main clauses that are closely related and share the subject (and are not too long/complex).

You would use a comma with und if it joins more complex independent clauses or if other comma rules apply, but not in a simple structure like this.

Why is it zwei Methoden and not zwei Methode?

Methode is a feminine noun:

Singular: die Methode
Plural: die Methoden

In zwei Methoden, the noun must be in the plural because zwei means “two,” and two of something is always plural. The noun itself needs the plural ending -n:

eine Methode – two methods → zwei Methoden
eine Studentin – two female students → zwei Studentinnen

What case is zwei Methoden, and how do you know?

zwei Methoden is in the accusative plural.

It is the direct object of vergleicht (what does the research compare? → two methods).
For feminine nouns, nominative and accusative look the same in the plural: die Methoden.
The presence of a transitive verb vergleicht and the meaning of the sentence tell you that zwei Methoden is the object, hence accusative.

Why is it die Theorie and not der or das Theorie?

Because Theorie is a feminine noun in German:

Singular: die Theorie
Plural: die Theorien

In the sentence, die Theorie is the direct object of erklärt (what does the research explain?). For feminine singular nouns, die is used for both nominative and accusative:

Nominative: Die Theorie ist kompliziert.
Accusative: Er erklärt die Theorie.

Here, it is accusative, but the article die looks the same in both cases.

What exactly does dahinter mean, and what is it referring to?

dahinter is a pronominal adverb built from:

da- (referring back to something previously mentioned)
hinter (the preposition “behind”)

So die Theorie dahinter literally means “the theory behind it.”

What “it” refers to depends on context. In this sentence, it most naturally refers to whatever is being studied—likely the two methods or the phenomenon they relate to. The sentence says that the research not only compares two methods but also explains the underlying theory behind them.

What’s the difference between dahinter, dazu, and darüber? Could I say die Theorie dazu instead?

These are all pronominal adverbs, but they express different relationships:

dahinter = behind it (spatial or metaphorically “underlying”)
- die Theorie dahinter → the theory behind it (underlying theory)
dazu = to it / on it / about it / for it (very context‑dependent)
- die Theorie dazu → the theory concerning it / related to it – more neutral
darüber = about it / over it
- die Theorie darüber → the theory about it, but slightly less idiomatic in this exact phrase.

You could say die Theorie dazu, but die Theorie dahinter strongly suggests “the underlying theory,” which fits academic writing well. dazu sounds a bit more general: the theory associated with it, not necessarily the deeper/underlying one.

Could I change the word order to Unsere Forschung vergleicht zwei Methoden und die Theorie dahinter erklärt?

No, not with the same meaning.

Unsere Forschung vergleicht zwei Methoden und erklärt die Theorie dahinter.

One subject (unsere Forschung)
Two verbs (vergleicht and erklärt) in a single main clause
Direct objects: zwei Methoden and die Theorie dahinter

If you say:

Unsere Forschung vergleicht zwei Methoden und die Theorie dahinter erklärt.

…it sounds incomplete and ungrammatical: die Theorie dahinter now looks like a new subject, but erklärt is missing its object.

To start a new clause with die Theorie dahinter as subject, you would need something like:

Unsere Forschung vergleicht zwei Methoden, und die Theorie dahinter erklärt vieles.
(“…and the theory behind them explains a lot.”)

But that changes the meaning completely.

Why is the verb in the second part also in second position (erklärt), even though there is no repeated subject?

In German, the finite verb must be in second position in a main clause.

In your sentence, there is one main clause with a compound predicate:

Subject: Unsere Forschung
Predicate: vergleicht zwei Methoden und erklärt die Theorie dahinter

You do not start the second part with a new subject because it’s the same subject. Instead, German allows:

Subject (1st position): Unsere Forschung
Verb 1 (2nd): vergleicht
Object 1: zwei Methoden
Conjunction: und
Verb 2: erklärt
Object 2: die Theorie dahinter

The rule about the verb being in second position applies to each independent clause, but here we don’t have two independent clauses; we have one clause with two verbs sharing the same subject.

Could I say Wir vergleichen zwei Methoden und erklären die Theorie dahinter instead of Unsere Forschung vergleicht …? Is there a difference?

Yes, that alternative is grammatically correct, and the difference is mainly stylistic:

Unsere Forschung vergleicht …
- More formal, impersonal, typical of academic abstracts and papers.
- Focus on the research project itself as an entity.
Wir vergleichen …
- More personal and direct, emphasizing the researchers.
- Common in presentations, talks, or less formal texts.

Both convey essentially the same action, but unsere Forschung sounds more like written academic style.

What tense is this, and does it mean “is comparing” or “compares”?

The tense is Präsens (present tense).

German Präsens can cover several English uses:

Our research compares two methods (general statement)
Our research is comparing two methods (currently ongoing project)
Sometimes even future, depending on context:
- Morgen vergleichen wir zwei Methoden. = “Tomorrow we’ll compare two methods.”

So Unsere Forschung vergleicht zwei Methoden und erklärt die Theorie dahinter can mean either “compares and explains” or “is comparing and explaining,” depending on context.