evaluation of the scale of swimming skills for preschool children

ACTA UNIVERSITATIS CAROLINAE, 

KINANTHROPOLOGICA Vol. Pag. 

CHARLES UNIVERSITY IN PRAGUE, FACULTY OF PHYSICAL EDUCATION AND SPORT 

DEPARTMENT OF KINANTHROPOLOGY 

EVALUATION OF THE SCALE OF SWIMMING SKILLS FOR 

PRESCHOOL CHILDREN 

JAN ŠTOCHL, IRENA ČECHOVSKÁ, VERONIKA PAVELKOVÁ 

SUMMARY 

This article deals with verification of validity, reliability, dimensionality and objectivity of the 

scale used for diagnosing swimming skills of pre-school children. The scale has been 

developed by the Department of Swimming at Charles University, The School of Physical 

Education and Sport. It consists of 7 items. Each item has been evaluated on five ordinal 

categories from 1 to 5. A sample of n=212 pre-school children has been evaluated in this 

study. The validity has been verified through a factor analysis, for the estimation of reliability 

the „test-retest“ method has been used. 

Keywords: Swimming of the preschoolers, evaluation, the scaling 

INTRODUCTION 

Modern trends in teaching of swimming lower down the age of the first contacts with 

water to the infant age. However, this swimming experience should be rather connected with 

question of diagnosing swimming level at preschool children. Empirical studies dealing with 

testing the pre-school children are not common in the Czech Republic, although their 

importance is obvious. „Swimming of pre-school children“ is a term which is traditionally 

used but which is not exact, because in this stage of education of swimming (called 

„preparatory swimming stage“) it considers basic swimming skills such as ducking the head 

under the water, breathing into the water, etc. Proper swimming movements would not be 

possible without acquiring these skills. Teaching one swimming stroke is the content of the 

next stage called „basic swimming stage“. 

There is often only the chronological age criterion used to enter the basic stage, although 

interindividual differences in adaptation to water are evident. The objective test describing the 

level of adaptation to water can be represented by a standardized scale evaluating readiness to 

start the basic swimming stage. 

In the Czech Republic, the Rehor´s standardized scale (1963) has been constructed for 

children from 10 to 12 years of age, but nowadays it does not correspond to the modern 

system of education of swimming. The issue of swimming of preschoolers is also discussed 

in articles by Šarinová (1999) and Čechovská (2002). The level of child’s preparedness to 

undergo the basic stage of swimming is important especially for less experienced instructors 

of swimming. The instructors do not have any objective test for evaluating the level of 

adaptation of the children to water environment. An appropriate evaluation scale should also 

be used to compare quality of teaching in various swimming schools. 

The scale suggested here has been developed by the Department of Swimming at Charles

University, The Faculty of Physical Education and Sport. It consists of seven following items. 

Each item is quantified on ordinary scale from 1 to 5 levels – categories (see Appendix). 

1) Head ducking 

2) Floating on front side of the body 

3) Floating on back side of the body 

4) Breathing into the water 

5) Diving 

6) Fishing out two objects 

7) Rotation around the lengthwise axis 

METHODS 

The research sample consisted of n=212 preschool children from 4 to 6 years old. This sample 

has not been supposed to be random but still represented a typical picture of Prague 

preschoolers and kindergarden children. The research has been organised in two phases. At 

first, the subsample of swimming experienced children has been tested. This sample contents 

101 children from various nurseries from Prague, who have benn attended the Swimming 

School of the Slavia sport club in Prague on a regular, once a week and who have gone 

through 28 lessons of prep-stage of education of swimming before being tested. In the 30th 

lesson a retest has been applied. In the second phase of the research the subsample of the 

beginners has been tested. This sample of beginners has been consisted of 111 children who 

completed 4 lessons of the education of pre-swimming. The retest has been carried out in the 

6th lesson. The time interval between the test and the retest has been two weeks. The sample 

of beginners has been contamined by some children with swimming experience, but it has 

been impossible to identify them. 

Three independent raters have been carried out the scale. They all have been assessed one 

child at the same time. 

For standardization of the scale following methods have been used: 

• To obtain the data, we chose the method of scale observation. 

• To evaluate dimensionality and construct validity we used a confirmatory factor 

analysis, (GFI = Bentler´s delta and Root Mean Square Residual coefficient) 

• To estimate a reliability of the scale a test-retest method (stability in time) has been 

used. 

• To state the objectivity (inter-rater reliability) of the scale a method of inter-rater 

agreement (through intraclass correlation coefficient) has been applied. 

Software used in this study: NCSS (correlations, descriptive statistics), SPSS (intraclass 

correlation coefficient), GEFA (factor analysis) 

HYPOTHESIS 

In the general basis outlined above and usual experience and findings, we assume: 

• Objectivity coefficient will be higher than 0.9 

• Dimensionality of the scale will be higher than 1. 

• The items such as „Head ducking“ and „Breathing into the water“ will be highly 

correlated 

• Estimations of coefficients of the construct validity in relation to the concept „level of 

adaptation on water environment“ criteria will be higher than 0.8.

RESULTS 

Dimensionality of the scale 

Dimensionality has been verified by GEFA. With regard to the structure of correlation 

submatrices of each rater it has been tested the hypothesis of unidimensionality of the scale. 

Following three matrices (from table 1 to table 3) have been tested. 

Table 1 Correlation matrix – Rater 1 

Ducking Front Back BreathingDiving Fishing Ducking 

Rotation 

out 

1,00 

Front 0,65 1,00 

Back 0,54 0,71 1,00 

Breathing 0,75 0,70 0,66 1,00 

Diving 0,63 0,64 0,59 0,65 1,00 

Fishing out 0,57 0,65 0,59 0,66 0,64 1,00 

Rotation 0,57 0,70 0,71 0,63 0,66 0,73 1,00 

Table 2 Correlation matrix - Rater 2 

Ducking Front Back BreathingDiving Fishing 

out Rotation 

Ducking 1,00 

Front 

0,66 1,00 

Back 0,55 0,75 1,00 

Breathing 0,71 0,67 0,61 1,00 

Diving 0,58 0,66 0,58 0,64 1,00 

Fishing out 0,65 0,72 0,64 0,72 0,70 1,00 

Rotation 0,53 0,73 0,71 0,61 0,67 0,77 1,00 

Table 3 Correlation matrix – Rater 3 

Ducking Front Back BreathingDiving Fishing 

out Rotation 

Ducking 1,00 

Front 

0,64 1,00 

Back 0,57 0,75 1,00 

Breathing 0,71 0,67 0,67 1,00 

Diving 0,62 0,66 0,63 0,65 1,00 

Fishing out 0,67 0,70 0,69 0,69 0,71 1,00 

Rotation 0,60 0,70 0,72 0,66 0,70 0,76 1,00 

Bentler´s delta, Root Mean square residual and Maximal values in residual matrices for 

each rater are in table 4:

Table 4 Coefficients of goodness of fit 

Bentler´s delta RMSR 

Maximal value in residual 

matrix (Least Square 

Method) 

Maximal value in residual 

matrix (Maximum 

Likelihood Method) 

Rater 1 0,996 0.031 0,109 0,111 

Rater 2 0,997 0,032 0,107 0,116 

Rater 3 0,998 0,023 0,084 0,092 

Values of Bentler´s delta (near 1) in conjunction with low correlations in residual 

matrices indicate so called. „Good fit“ of hypothesis. From Tables 7 it is obvious that 

unifactor model is able to explain Heterotrait-Monomethod submatrices of all 3 raters. All 

items „measure“ the same concept. The scale is unidimensional. 

Evaluation of factor validity 

Confirmatory factor analysis creates coefficients of theoretical validity to latent criterion. 

In this case, it has been defined criterion as the „level of adaptation on water“. 

Factor validity of the scale has been evaluated by GEFA (Generalized Factor Analysis) 

software. This software analysis the data by the least squares method and by method of 

maximum likelihood. 

Coefficients of theoretical validity to criterion „level of adaptation to water“ generated 

by GEFA are following: 

Table 5 Estimation of validity coefficients 

Rater 1 Rater 2 Rater 3 

LSM MLM LSM MLM LSM MLM 

Ducking 0,761 0,764 0,744 0,742 0,764 0,761 

Front 

0,844 0,844 0,868 0,863 0,838 0,837 

Back 0,784 0,792 0,784 0,790 0,818 0,823 

Breathing 0,842 0,836 0,809 0,801 0,820 0,812 

Diving 0,784 0,782 0,781 0,783 0,803 0,804 

Fishing out 0,793 0,795 0,872 0,871 0,863 0,863 

Rotation 0,831 0,829 0,829 0,839 0,845 0,850 

LSM = The Least Square Method 

MLM = Maximum Likelihood Method 

From the Table 5 it is obvious that: 

• Estimated coefficients of validity for each item are in range 0,742 – 0,872. 

• The lowest validity to criterion has the item „ head ducking“ . 

• Estimated coefficients are quite homogenous, therefore all items can be considered as 

parallel. 

• with regard to high values of validity coefficients, the scale obtains good theoretical 

validity.

Evaluation of reliability 

For analysis of the reliability the test-retest method has been used. In this method, 

estimations of reliability coefficients are represented by correlations between test and retest. 

In the Tables 6 to 8 the summary includes points reached in individual items of the scale 

and summary of points reached in all seven items of testees in test and retest.113 children 

participated in retest (out of total 212 children). 

Table 6 Estimates of reliability coefficient - Rater 1 

Ducking Front Back Breathing Diving Fishing 

Rotation Sum 

out 

Ducking ret. 0,62 0,63 0,60 0,69 0,65 0,52 0,58 0,70 

Front ret. 0,60 0,79 0,69 0,69 0,73 0,67 0,70 0,83 

Back ret. 0,50 0,78 0,71 0,60 0,62 0,58 0,68 0,75 

Breathing ret. 0,67 0,62 0,61 0,74 0,57 0,58 0,57 0,73 

Diving ret. 0,60 0,71 0,68 0,72 0,75 0,67 0,71 0,82 

Fishing out ret. 0,57 0,59 0,65 0,67 0,74 0,73 0,76 0,82 

Rotation ret. 0,58 0,69 0,70 0,66 0,69 0,66 0,73 0,80 

Sum ret. 0,65 0,79 0,78 0,77 0,78 0,76 0,81 0,92 



Rotation Sum 

out 

Ducking ret. 0,65 0,63 0,54 0,66 0,54 0,57 0,48 0,67 

Front ret. 0,60 0,80 0,69 0,61 0,65 0,71 0,74 0,82 

Back ret. 0,52 0,75 0,69 0,63 0,62 0,66 0,71 0,78 

Breathing ret. 0,61 0,67 0,60 0,66 0,59 0,66 0,57 0,73 

Diving ret. 0,53 0,70 0,66 0,63 0,74 0,71 0,73 0,79 


Rotation ret. 0,54 0,71 0,67 0,63 0,70 0,73 0,76 0,81 

Sum ret. 0,63 0,82 0,75 0,73 0,76 0,82 0,82 0,92 



Rotation Sum 

out 

Ducking ret. 0,62 0,58 0,49 0,63 0,57 0,54 0,51 0,63 

Front ret. 0,64 0,73 0,64 0,61 0,61 0,70 0,70 0,77 

Back ret. 0,54 0,73 0,69 0,60 0,62 0,65 0,76 0,77 

Breathing ret. 0,61 0,63 0,55 0,60 0,51 0,52 0,52 0,64 

Diving ret. 0,55 0,61 0,61 0,56 0,69 0,63 0,57 0,69 


Rotation ret. 0,56 0,66 0,74 0,63 0,67 0,75 0,76 0,80 

Sum ret. 0,66 0,78 0,78 0,72 0,76 0,82 0,80 0,90

From the tables above it is obvious that: 

1) Reliability coefficients of individual item are within 0.6 to 0.79, the average is 0.72, 

variance 0,0034 and standard deviation 0,058 

2) Average of reliabilities of items of the scale: 

• Reliability of item „ Head ducking “ is 0,63 

• Reliability of item „Floating on front“ is 0,77 

• Reliability of item „Floating on back “ is 0,69 

• Reliability of item „Breathing into the water“ is 0,67 

• Reliability of item „Diving“ is 0,73 

• Reliability of item „fishing out 2 objects“ is 0,77 

• Reliability of item „Rotation around the lengthwise axis“ is 0,75 

3) Reliability of total summary of points: 

• Rater 1 reached 0,92 

• Rater 2 reached 0,92 

• Rater 3 reached 0,90. 

According to the results of reliability, the scale can be classified as successful. 

Evaluation of objectivity 

So called objectivity as a specific form of reliability of the scale has been evaluated as 

inter-rater agreement among three independent raters. The estimations of objectivity 

coefficients at individual items of the scale are shown in the Tables 9 to15: 

Table 9 Item „Head ducking “ 


Rater 1 1 0,90 0,85 

Rater 2 0,90 1 0,86 

Rater 3 0,85 0,86 1 

Table 10 Item „Floating on front“ 


Rater 1 1 0,92 0,90 

Rater 2 0,92 1 0,92 

Rater 3 0,90 0,92 1

Table 11 Item „Floating on back“ 


Rater 1 1 0,87 0,89 

Rater 2 0,87 1 0,88 

Rater 3 0,89 0,88 1 

Table 12 Item „Breathing into water“ 


Rater 1 1 0,87 0,85 

Rater 2 0,87 1 0,83 

Rater 3 0,85 0,83 1 

Table 13 Item „Diving“ 


Rater 1 1 0,88 0,90 

Rater 2 0,88 1 0,90 

Rater 3 0,90 0,90 1 

Table 14 Item „Fishing out 2 objects“ 


Rater 1 1 0,94 0,91 

Rater 2 0,94 1 0,94 

Rater 3 0,91 0,94 1 

Table 15 Item „Rotation around the lengthwise axis“ 


Rater 1 1 0,87 0,88 

Rater 2 0,87 1 0,88 

Rater 3 0,88 0,88 1

From figures of given correlations it is obvious that: 

1) Coefficients of objectivity are in range 0,83 – 0,94. 

2) The highest estimation of objectivity applies for item „Fishing out 2 objects“ 

3) The lowest estimation of objectivity applies for items „Breathing into the water“ , 

„Head ducking“ a „Floating on back“ . 

4) The scale reaches high objectivity . 

For the global picture of interrater reliability the intraclass coefficient (from one way 

random ANOVA model) has been used (see Table 16). 

Table 16 Intraclass coefficients of items 

Intraclass coefficient 

Head ducking 0,924 

Floating on front 0,913 

Floating on back 0,894 

Breathing into the water 0,881 

Diving 0,915 

Fishing out 2 objects 0,956 

Rotation around the lengthwise axis 0,867 

From the table above it is obvious that: 

1) the highest interrater agreement has item “Fishing out 2 objects” 

2) the lowest interrater agreement has item “Rotation around the lengthwise axis”. This 

value is still high enough to use this item in the scale. 

DISCUSSION 

The process of evaluation of the scale has been divided into various parts. At first, it 

has been modified used, but not standardized scale. Together with experts from the 

Department of swimming at FTVS UK the scale has been made according to the standard 

program of „prep-stage of swimming education“. Insufficient item’s formulations have been 

removed during a pre-research period. After analysis of objectivity, various insufficiencies 

have been found in formulations of categories of items. A certain discord among raters has 

been appeared due to insufficient definitions of terms “sufficient persistence“ etc. 

In this research children from Prague have been used. Parents of these children have 

been interested in that their children would swim. It means that sample of children has not 

corresponded to typical children in the Czech Republic. Also the age of the children could be 

a problem. Although their age was from 4 to 6, the biological age could be between 2 and 8. 

Data have been contaminated by errors, which occur regularly at this type 

(observative) of research. Moreover, error of contamination of beginners and advanced 

swimmers has been appeared. A sum of all points reached in all items seems to be the most 

convenient method to evaluate a swimming efficiency of a testee .Evaluation of level of water 

adaptation based on child’s point reached in partial item is not recommended because of low 

item´s reliability. Reasons of low reliability of partial items can be seen both in a progress of 

testees and in children’s knowledge of the items during the retest. 

Due to similarity of items, optimal reduction of the scale could be discussed. 

Estimations of reliability after removing several items can be predicted by Spearman-Brown

formula. Thus, it is not recommended to reduce the scale about more than one item. In case of 

any reduction of items, the most convenient item is „ head ducking „ due to its low validity 

However, the scale in general is not time consuming and therefore reduction is not necessary. 

Hypothesis about multidimensionality of the scale has not been proved. On the 

contrary, it is obvious that all items „measure“ one trait. 

Another problem is the number of categories of each item. While using the scale, a 

vast number of testees reach the maximum of „points“, although interindividual differences in 

adaptation on water are detectable even among these individuals. In other words, the scale is 

not „sensitive“ enough. More categories in each item would ensure better differentiation 

among „advanced“ children. 

„ Head ducking „ and „ Breathing into the water“ are very similar items and that is 

why the hypothesis considering correlations between those item has been constructed. The 

analysis has proved close relation between these items, although it has not been as close as we 

have expected. 

The item "Head ducking" is commonly recognized diagnostic tool for evaluating the 

level of adaptation on water, although it measures “adaptation on water“ less than other items. 

It can be explained through content analysis of other items of the scale. It is obvious, that 

almost all remaining items cover the particular skill of „ Head ducking“ and thus has lower 

validity coefficient. 

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Appendix The scale evaluating swimming skills of pre-school children 

1. Head ducking 

5 b. whole head under the water, carried out easily with persistence 

4 b. whole head under the water, carried out quickly, no persistence 

3 b. not complete „ducking“ (either eyes or ears stay above the water surface) 

2 b. only quick ducking of a face , eyes and ears stay above the water surface 

1 b. not performed at all 

2. Floating on front side of the body 

5 b. floating position taken up easily, without any help ,with persistence 

4 b. floating position taken up quickly, without any help, without sufficient persistence 

3 b. floating position taken up with teacher’s help (hands on front side of the body) 

2 b. floating position even with teacher’s help only partially indicated 


3. Floating on back side of the body 

5 b. floating position taken up easily, without any help ,with persistence 

4 b. floating position taken up quickly, without any help, without sufficient persistence 

3 b. floating position taken up with teacher’s help (hands under the buttocks) 

2 b. floating position with teacher’s help only partially indicated 


4. Breathing into the water 

5 b. deep complete expiration together with head ducking, carried out easily 

4 b. only mouth expiration, carried out quickly 

3 b. either eyes or ears stay above the water surface 

2 b. mouth only partially under the water surface 

1 b. not performed at all

5. Diving 

5 b. independent, decisive leg first dive , distinguishable take off, flight, and controlled fall phase 

4 b. independent leg first dive , individual phases not clearly distinguished 

3 b. individually performed fall into the water , not completely fixed body position 

2 b. additional floating equipment or help requested 


6. Fishing out 2 objects 

5 b. confident fishing out of 2 objects after a head long dive, apparent visual control of objects under 

the water 

4 b. fishing out 2 objects, seeking the objects 

3 b. fishing out 1 object only 

2 b. ducking only, objects not fished out 


7. Rotation around the lengthwise axis 

5 b. complete turn, hold, floating position kept throughout the task 

4 b. floating positions interfered while performing the task 

3 b. floating positions only indicated or are not detectable while performing the task 

2 b. turn carried out with teacher’s help only 


Mgr. Jan Štochl 

Charles University 

Faculty of Physical education and Sport 

Department of Kinanthropology 

José Martího 31, 162 52 Prague 

The Czech Republic 

Email: Stochl@ftvs.cuni.cz

evaluation of the scale of swimming skills for preschool children

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