Learn Hardcore Japanese: bunbougu ha konbini yori ookii mise no hou ga yasuikoto ga ooi desu. - Stationery is often cheaper at big stores than at convenience stores.

If we used が (文房具が), it would sound like we are identifying stationery as the specific thing that is cheap, in contrast to something else, and the sentence would feel odd in this context. The point here is not “stationery (as opposed to other products) is cheap,” but “regarding stationery, here is a general observation about where it’s cheaper.”

So 文房具は sets the stage: “Talking about stationery, …”

How should I understand コンビニより大きい店 as a unit?

コンビニより大きい店 literally means “shops that are bigger than convenience stores.”

Breakdown:

コンビニ – convenience store
より – “than” (standard of comparison)
大きい – big
店 – store / shop

Structure: AよりB = “B is more X than A”

So:

コンビニより大きい店
= “stores that are larger than convenience stores.”

There is no extra particle after コンビニ because より itself plays that grammatical role.

What does のほう in 大きい店のほうが do? Could we just say 大きい店が安い?

のほう literally means “the side” or “the direction,” and in comparisons it marks which side is preferred / wins.

AよりBのほうが安い
= “Compared to A, B is cheaper (B’s side wins).”

So:

コンビニより大きい店のほうが安い
= “Compared with convenience stores, the larger shops are cheaper.”

If you say:

コンビニより大きい店が安い

it’s grammatically OK and understandable, but のほうが makes the comparison more explicit and natural, especially in spoken Japanese. Without のほう, the sentence can sound a bit blunt or slightly less balanced in its comparison.

So:

大きい店が安い = “Big stores are cheap.” (simple statement)
コンビニより大きい店のほうが安い = “Between the two, big stores (rather than convenience stores) are cheaper.”

How is the whole phrase コンビニより大きい店のほうが structured inside the sentence?

You can think of the sentence in chunks:

文房具は – As for stationery,
コンビニより大きい店のほうが – the bigger stores (compared to convenience stores)
安いことが多いです – are often cheaper.

So the subject phrase is:

コンビニより大きい店のほうが

and the predicate is:

安いことが多いです

Put together:
“As for stationery, the larger stores (rather than convenience stores) are often cheaper.”

What does こと do in 安いことが多いです?

こと is a nominalizer: it turns a verb or adjective phrase into a noun-like thing.

安い – “is cheap” (adjective)
安いこと – “the fact of being cheap” / “cases where it is cheap”

Then:

安いことが多いです
literally = “There are many instances of it being cheap.”
natural English = “It is often cheap.”

So 安いことが多い ≈ “it’s often cheap,” but built as:

[being cheap] + [are many]

This pattern is very common:

雨が降ることが多い – It often rains.
間違えることが多い – I often make mistakes.

Why is it 安いことが多いです instead of something like よく安いです?

よく is an adverb meaning “often,” but with adjectives like 安い, よく安いです is not the most natural way to say “is often cheap”.

More natural patterns are:

安いことが多いです – There are many times when it is cheap.
たいてい安いです – It is usually cheap.
安く売られていることが多いです – It is often sold cheaply.

よく works more naturally with verbs:

よく買います – I often buy it.
よく行きます – I often go there.

So to say “often cheap,” 安いことが多い is a very standard and natural expression.

Why is it 安いことが多いです and not 安いですことが多いです?

When you use こと to nominalize, you attach it to the plain form, not the です-form:

adjective plain form: 安い
adjective polite form: 安いです

The rule here is:

[plain form] + こと

So:

安いこと ✅
安いですこと ❌ (unnatural / ungrammatical in normal modern speech)

Same with verbs:

食べること (to eat / eating) – correct
食べますこと – incorrect in normal usage

That’s why it must be 安いことが多いです.

Why is there no plural marker on 店 even though the English meaning is “stores”?

Japanese usually doesn’t mark plural for regular nouns unless it’s needed for clarity or emphasis.

店 can mean “a store” or “stores,” depending on context.

Here, because we are talking about general tendencies (“large stores are often cheaper”), the reader naturally understands 店 as plural, “stores.”

So:

大きい店のほうが安いことが多いです。
= “Larger stores are often cheaper.” (even though 店 is not explicitly plural)

Could we say お店 instead of 店? Is there a difference?

Yes, you can say お店 instead of 店:

コンビニより大きいお店のほうが安いことが多いです。

お店 adds a polite / slightly softer nuance.
店 is neutral and perfectly fine in this kind of general statement.

So the difference is mostly politeness and tone, not meaning:

店 – neutral “store/shop”
お店 – more polite / friendly “(your/the) shop”

Could the word order be changed, for example putting 文房具 later in the sentence?

Yes, you can move 文房具は a bit, although the original is the most natural:

Original:

文房具はコンビニより大きい店のほうが安いことが多いです。

You might also see, for emphasis:

コンビニより大きい店のほうが、文房具は安いことが多いです。
“At bigger stores than convenience stores, stationery is often cheaper.”

Both are grammatical.
The main thing is that は still marks 文房具 as the topic, and コンビニより大きい店のほうが still works as the subject of the predicate 安いことが多いです in some sense (“the larger stores tend to be cheap (for stationery)”).

In everyday Japanese, the original ordering is natural and clear, so it’s good to imitate that.