Question

我需要计算这样的值列表的第90个百分位数：

我将如何进行计算？我知道答案是0.0713,9。有什么建议吗？

DECLARE @Temp TABLE(DATA float)

INSERT INTO @Temp VALUES(0.0099)
INSERT INTO @Temp VALUES(0.0129)
INSERT INTO @Temp VALUES(0.0031)
INSERT INTO @Temp VALUES(0.0219)
INSERT INTO @Temp VALUES(0.2632)
INSERT INTO @Temp VALUES(0.0124)
INSERT INTO @Temp VALUES(0.0493)
INSERT INTO @Temp VALUES(0.05) 
INSERT INTO @Temp VALUES(0.0433)

SELECT DATA
FROM @Temp
ORDER BY DATA ASC

--90th percentile 
SELECT ((
        SELECT TOP 1 DATA
        FROM   (
                SELECT  TOP 90 PERCENT DATA
                FROM    @Temp
                WHERE   DATA IS NOT NULL
                ORDER BY DATA
                ) AS A
        ORDER BY DATA DESC) + 
        (
        SELECT TOP 1 DATA
        FROM   (
                SELECT  TOP 10 PERCENT DATA
                FROM    @Temp
                WHERE   DATA IS NOT NULL
                ORDER BY DATA DESC
                ) AS A
        ORDER BY DATA ASC)) / 2.0

Answer 1

Source

百分位数（或百分位数）是统计中使用的度量，指示一组观察值中观察到的给定百分比下降的值。例如，第20百分位数是低于其中20％的观察结果的值（或分数）。

百分位数没有标准定义

最近等级方法：

SELECT DATA
FROM (
    SELECT 
        DATA, 
        COUNT(1) OVER (PARTITION BY NULL) As N, 
        ROW_NUMBER() OVER (ORDER BY DATA) AS i
    FROM @Temp) t
WHERE
    i = ROUND(N * 90.00 / 100.00, 0, 0)

最近等级之间的线性插值方法：

DECLARE @P real = 90.00

SELECT MAX(tt.Pv)
FROM (
    SELECT 
        (CASE 
            WHEN i = k THEN DATA
            WHEN k = 0 AND P = MIN(CASE WHEN P > @P THEN P END) OVER (PARTITION BY NULL) THEN 
                DATA + N * (@P - P) / 100 * (MIN(CASE WHEN P > @P THEN DATA END) OVER (PARTITION BY NULL) - DATA)
            ELSE 0
        END) AS Pv
    FROM (
        SELECT 
            *,
            100.00 / N * (i - 1.00 / 2.00) AS P,
            CASE
                WHEN @P < 100.00 / N * (1 - 1.00 / 2.00) THEN 1 
                WHEN @P > 100.00 / N * (N - 1.00 / 2.00) THEN N
                WHEN @P = 100.00 / N * (i - 1.00 / 2.00) THEN i
                WHEN @P > 100.00 / N * (i - 1.00 / 2.00) THEN i
                ELSE 0
            END AS k
        FROM (
            SELECT 
                DATA, 
                COUNT(*) OVER (PARTITION BY NULL) As N, 
                ROW_NUMBER() OVER (ORDER BY DATA) AS i
            FROM @Temp) ti) t
    ) tt;

Answer 2

0.0713不是正确答案，procentile是列表中的值

    DECLARE @Temp TABLE(DATA float)

INSERT INTO @Temp VALUES(0.0099)
INSERT INTO @Temp VALUES(0.0129)
INSERT INTO @Temp VALUES(0.0031)
INSERT INTO @Temp VALUES(0.0219)
INSERT INTO @Temp VALUES(0.2632)
INSERT INTO @Temp VALUES(0.0124)
INSERT INTO @Temp VALUES(0.0493)
INSERT INTO @Temp VALUES(0.05) 
INSERT INTO @Temp VALUES(0.0433) 

select max(case when rownum*1.0/numrows <= 0.9 then DATA end) as percentile_90th
from (select DATA,
             row_number() over (order by DATA) as rownum,
             count(*) over (partition by NULL) as numrows
      from @Temp
      where DATA is not null
     ) t

FROM T-SQL: Calculating the Nth Percentile Value from column

Answer 3

PERCENTILE_CONT功能：

DECLARE @Temp TABLE(DATA float)

INSERT INTO @Temp VALUES(0.0099)
INSERT INTO @Temp VALUES(0.0129)
INSERT INTO @Temp VALUES(0.0031)
INSERT INTO @Temp VALUES(0.0219)
INSERT INTO @Temp VALUES(0.2632)
INSERT INTO @Temp VALUES(0.0124)
INSERT INTO @Temp VALUES(0.0493)
INSERT INTO @Temp VALUES(0.05) 
INSERT INTO @Temp VALUES(0.0433)

SELECT
    PERCENTILE_CONT(0.9) WITHIN GROUP (ORDER BY e.DATA) OVER () AS PERCENTILE
FROM @Temp AS e

如何计算SQL Server中的第90个百分位数

3 个答案: