据: according to (a source)
【六19】介词 / prepositions (凭借、依据)
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
据 + source, + statement: 据 opens the sentence and says where the information comes from: 据统计, 据报道, 据专家介绍, 据老乡说. When the source is a person, a verb of speaking must follow it (说, 介绍); when it is a document or a figure (统计, 报道, 预报), the verb is optional.
Register: the press, reports, the voice-over of a documentary. 据说 ("it is said that") is a word of its own, common in speech too, that passes on hearsay without naming anyone. More formal: 据了解, 据悉. In the first person: 据我所知 (hsk5-g30).
Difference from 根据 / 按照 (hsk3-g37, hsk4-g15): 根据 gives the basis for a decision or an argument (根据天气预报决定去不去), 按照 a rule to follow. 据 only quotes the source of a claim, and what follows is a piece of information, not an instruction.
Examples
据说，这家店下个月就要关门了。
Jùshuō, zhè jiā diàn xià ge yuè jiù yào guānmén le.They say this shop is closing next month.
据我的朋友说，那家医院的医生很有耐心。
Jù wǒ de péngyou shuō, nà jiā yīyuàn de yīshēng hěn yǒu nàixīn.According to a friend of mine, the doctors at that hospital are very patient.
据天气预报，明天北方会有大雪。
Jù tiānqì yùbào, míngtiān běifāng huì yǒu dàxuě.According to the weather forecast, there will be heavy snow in the north tomorrow.
据统计，去年来这座古城旅游的人比前年多了百分之二十。
Jù tǒngjì, qùnián lái zhè zuò gǔchéng lǚyóu de rén bǐ qiánnián duō le bǎi fēn zhī èrshí.According to statistics, last year the old town had twenty percent more visitors than the year before.
据报道，这条地铁线路将在明年年底通车。
Jù bàodào, zhè tiáo dìtiě xiànlù jiāng zài míngnián niándǐ tōngchē.According to reports, this metro line will open at the end of next year.
据专家介绍，这种鸟每年春天都会飞回这个湖边。
Jù zhuānjiā jièshào, zhè zhǒng niǎo měi nián chūntiān dōu huì fēihuí zhège hú biān.According to one expert, this bird flies back to this lake every spring.
Common mistakes
✗ 根据说，他已经搬走了 → ✓ 据说，他已经搬走了 (据说 is a word of its own; 根据 does not combine with 说).
✗ 据我的朋友，他搬家了 → ✓ 据我的朋友说，他搬家了 (a person as the source needs a verb of speaking).