Estimating chart for the correlation coefficient

Form of connection	Direct (+)	Inverse (-)
Estimate small (low, weak)	From 0,0 till 0,3	From 0,0 till -0,3
Middle	From 0,3 till 0,7	From -0,3 till -0,7
Big (high, strong)	From 0,7 till 1,0	From -0,7 till –1,0

 

The correlation coefficient is calculated by the method of squares or method of classes. Class method (express-method) by Spearman. Calculation formula is as follows:

- coefficient of class correlation,

N - number of paired members,

D – difference between original numbers of classes.

1 and 6 – constant

 

 For instance, at school of a city “S” percentage of vaccination and, respectively, the sickness rate (infant infections) were estimate data (chart).

Table 27

Percentage of vaccination and sickness rate at a school of city “S”

Vaccination % (X)	Sickness rate% (Y)	Class numbers		Difference of classes	Class different sq.
		X	Y
15,0	22,0	1	4	-3	9
20,0	28,0	2	5	-3	9
25,0	18,0	3	3	0	0
30,0	14,0	4	2	2	4
35,0	10,0	5	1	4	16

Sd² = 38

Let’s put numerical data into Spearman’s formula:

=

ESTIMATION OF RELIABILITY

 

VARIANT 1

At study of progress of the students of medical institute – not working and combination of study with job – were the following data at not working given a number X₁=14,(m₁=±0,09) and combining study with job X₂=3,65 (m₂=±0,05) are received.

VARIANT 2

At study of work capacity at the patients suffering from myocardial infarction at presence hypertensive disease and without it(her),the following data were received date come back to work which has transferred a myocardial infarction hypertensive disease by illness P₁=61,0% (mp₁=±4,0%), without hypertensive disease is equal to P₂=75,0% (mp₂=±3,0%).

VARIANT 3

At study of frequency of suppuration after appendectomy in 2groups patients of which in one penicillin is applied and in the other not applied, the following data were received, in the first group P₁ suppuration had 30,0% of the patients (mp₁=±5,1%), in 2^nd group 40,0% (mp₂=±5,4%)

VARIANT 4

At the medical student investigated pulse rate (one minute) before passing an examination. Often of pulse on the average before examination (X₁) has made 94,2 impacts one minute (m₁=±3,9 of impact one minute), after examination X₂=82,0 of impact one minute (m₂=±4,1 impact one minute).

VARIANT 5

In groups patients with coronary arteriosclerosis research on the contents of cholesterol in blood. The contents of cholesterol in blood before application of choline on average

(X₁) has made 231,0 mg% (m₁=±4,0mg%), after application of choline X₂=204,0mg% (m₂=±3,0mg%).

VARIANT 6

At medical student investigated maximal arterial pressure before and after passing examinations. Before examinations on the average (X₁) has made 127,2mmHg (m₁=±3,0mmHg), after delivery X₂=117,0mmHg (m₂=±4,0mmHg).

VARIANT 7

At study of parameters of lethality in 2 urban hospitals were received the following data. Hospital and parameter of lethality in (P₁) was equal 2,7%(m₁=±0,07%), in hospital P₂=3,2% (m₂=±0,04%). The structure of the patients on branches was approximately identical.

VARIANT 8

At study of influence anabolic hormones at a myocardial infarction on albumin exchange the following data. General fiber before treatment (P₁) were received has made 7,14% (mp₁=±0,17%), after treatment (P₂) =8,04% (mp₂=±0,12%).

ESTIMATION CORRELATION

VARIANT 1

Table 28