2021-11-03

Walter A Shewhart om data

Walther A Shewhart
1891-1967

Rule 1. Original data should be presented in a way that will preserve the evidence in the original data for all the predictions assumed to be useful.

Rule 2. Any summary of a distribution of numbers in terms of symmetric functions should not give an objective degree of belief in any one of the inferences or predictions to be made therefrom that would cause human action significantly different from what this action would be if the original distributions had been taken as evidence.

Walter A Shewhart (1939). Statistical method from the viewpoint of quality control, p. 88

Shewhart på nudansk

Fire datasæt

x y1 y2 y3 y4
1 41.33367 25.35785 41.70929 41.70929
2 25.35785 15.31526 43.28499 36.71693
3 15.31526 26.84944 47.12764 31.40539
4 33.45710 22.74938 41.33367 33.14598
5 26.84944 11.64422 36.71693 25.35785
6 33.32034 25.65485 33.32034 15.31526
7 43.28499 25.17042 34.24932 15.98739
8 22.74938 18.13094 29.38817 25.65485
9 11.64422 15.98739 31.40539 25.17042
10 25.65485 19.70717 33.45710 33.45710
11 25.17042 15.79783 32.24982 33.32034
12 18.13094 29.38817 34.54066 43.28499
13 15.98739 41.33367 33.14598 47.12764
14 33.14598 33.45710 25.17042 34.24932
15 31.40539 33.32034 22.74938 32.24982
16 19.70717 43.28499 26.84944 22.74938
17 34.54066 33.14598 25.35785 18.13094
18 15.79783 31.40539 25.65485 15.79783
19 34.24932 34.54066 18.13094 11.64422
20 41.70929 34.24932 19.70717 19.70717
21 29.38817 41.70929 15.31526 26.84944
22 32.24982 32.24982 15.98739 34.54066
23 36.71693 36.71693 15.79783 29.38817
24 47.12764 47.12764 11.64422 41.33367

Fire sammendrag

key n min median max mean sd
y1 24 11.644 30.397 47.128 28.929 9.681
y2 24 11.644 30.397 47.128 28.929 9.681
y3 24 11.644 30.397 47.128 28.929 9.681
y4 24 11.644 30.397 47.128 28.929 9.681

Data varierer – over tid og sted

… nu med kontroldiagrammer

Sundhedskvalitet ifølge SUM, DR og KL

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