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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>October</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Computational modelling of stochastic processes for learning research</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Oleksandr H. Kolgatin</string-name>
          <xref ref-type="aff" rid="aff3">3</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Larisa S. Kolgatina</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Nadiia S. Ponomareva</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>H. S. Skovoroda Kharkiv National Pedagogical University</institution>
          ,
          <addr-line>29 Alchevskyh Str., Kharkiv, 61002</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Kharkiv University of Technology “STEP”</institution>
          ,
          <addr-line>9/11 Malomyasnytska Str, Kharkiv, 61000</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Kryvyi Rih State Pedagogical University</institution>
          ,
          <addr-line>54 Gagarin Ave., Kryvyi Rih, 50086</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff3">
          <label>3</label>
          <institution>Simon Kuznets Kharkiv National University of Economics</institution>
          ,
          <addr-line>9A Science Ave., Kharkiv, 61166</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2022</year>
      </pub-date>
      <volume>1</volume>
      <issue>2021</issue>
      <fpage>0000</fpage>
      <lpage>0001</lpage>
      <abstract>
        <p>The objectives of our work were to use computer-based statistical modelling for comparison and systematisation of various approaches to non-parametric null hypothesis significance testing. Statistical model for simulation of null hypothesis significance testing has been built for educational purpose. Fisher's angular transformation, Chi-square, Mann-Whitney and Fisher's exact tests were analysed. Appropriate software has been developed and gave us possibility to suggest new illustrative materials for describing the limitations of analysed tests. Learning researches as the method of understanding inductive statistics have been suggested, taking into account that modern personal computers provide acceptable time of the simulations with high precision. The obtained results showed low power of the most popular non-parametric tests for small samples. Students can't analyse the test power at traditional null hypothesis significance testing, because the real diferences between samples are unknown. Therefore, it is necessary to change the accents in Ukrainian statistical education, including PhD studies, from using null hypothesis significance testing to statistical modelling as a modern and efective method of proving the scientific hypothesises. This conclusions correlate with observed scientific publications and the recommendation of the American Statistical Association.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;computational modelling</kwd>
        <kwd>computer-based simulation</kwd>
        <kwd>statistical hypothesis significance testing</kwd>
        <kwd>education</kwd>
        <kwd>learning research</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <sec id="sec-1-1">
        <title>1.1. Statement of the problem</title>
        <p>
          Computational modelling and using the computer-based models for simulation is an essential
part of educational content and methodology. From one hand, computer-based simulation
becomes one of the main method of pedagogical research that brings new facilities in forecast
and proving the eficiency of new pedagogical technologies. From the other hand computational
modelling and computer-based simulations provided by students give them new experience
in dificult sided of educational content, facilitate competences in independent work and
researcher’s competences [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ]. Thus, students’ learning research with computational simulations
has been developed as a method for improving students’ self management through creative
learning activity [
          <xref ref-type="bibr" rid="ref2 ref3">2, 3</xref>
          ]. Semerikov et al. [
          <xref ref-type="bibr" rid="ref4 ref5">4, 5</xref>
          ] have suggested to use computer simulation of
neural networks using spreadsheets. These results give us possibility to introduce this modern
technology in educational process of wide kinds of educational programs that are not directly
connected with computer science. The elements of technique of using CoCalc at studying topic
“Neural network and pattern recognition” of the special course “Foundations of Mathematic
Informatics” are shown in the works of Markova et al. [
          <xref ref-type="bibr" rid="ref6">6</xref>
          ]. The method of computational
simulation and modelling is supported by work of Modlo and Semerikov [
          <xref ref-type="bibr" rid="ref7">7</xref>
          ], where new tools
for modelling of electromechanical technical objects in cloud-based learning environment have
been suggested. Khazina et al. [
          <xref ref-type="bibr" rid="ref8">8</xref>
          ] also considered computer modelling as a scientific means of
training. So we can conclude that computational modelling and simulation is the popular and
actual learning method. This field of research is very interesting for our present study, because
it promotes development of computational modelling as a method of learning researches.
        </p>
        <p>
          One of such fields of pedagogical investigations, where new information technologies can
provide new level of understanding the modelled processes, is comparative pedagogical
experiment and statistical hypothesis testing as a part of one. Computer-based statistical analysis
becomes a major part of the monitoring of the learning resources quality [
          <xref ref-type="bibr" rid="ref9">9</xref>
          ]. In our work, we
consider statistical processing of results of pedagogical experiment as one aspect of pedagogical
research. Traditionally this problem is solved by methods of mathematical statistics on the
basis of statistical hypothesis testing. Two hypotheses are put forward: the null hypothesis,
which states that there are no diferences between compared random variables in the studied
parameter, and the alternative hypothesis, which argues that the observed diferences are caused
by the studied impact. A researcher uses some criterion that integrates the observed diferences
in the numeric form and calculates the probability of obtaining the same or larger diferences in
random process to accept one of those hypothesises. The number of participants in pedagogical
studies is usually small, so we accept alternative hypothesis, if the probability of the type I
error (the probability that the observed diferences are due to random factors) does not exceed
5 %. Understanding the essence of statistical hypothesis testing is a hard problem. Thus, Sotos
et al. [
          <xref ref-type="bibr" rid="ref10">10</xref>
          ] pointed the common misconceptions about statistical inference. They noted that in
response to the persistence of the misconceptions, educational researchers and practitioners
have initiated and promoted a thorough reform for teaching statistics. And one direction of
this reform was the importance of integrating technology in the statistics classroom, using
simulations to help students understand the ideas behind statistical processes [
          <xref ref-type="bibr" rid="ref10">10</xref>
          ]. Problems of
using statistical hypothesis tests are so deep that discussions continue even now, after more
than a hundred years after implementation this approach into the science. For example,
scientists discuss the problem of dichotomization of p-values, because it makes matters worse
(Wasserstein et al. [
          <xref ref-type="bibr" rid="ref11">11</xref>
          ]) and suggest to describe the data using other approaches (McShane et al.
[
          <xref ref-type="bibr" rid="ref12">12</xref>
          ]). The use of computer-based modelling provides a new look at the system of inductive
methods of statistics, gives possibility to highlight the most powerful methods and to determine
the limits of their applicability, which is particularly important in psychological and pedagogical
studies, where samples are small [
          <xref ref-type="bibr" rid="ref13">13</xref>
          ].
        </p>
        <p>Otherwise, the practice of statistical data analysis in Ukrainian pedagogical researches
is grounded on traditional approach. So we need to show educational community modern
computer-based techniques for data analysis that are based on simulation of stochastic
processes. We also need to show comparison of these techniques with traditional criteria for null
hypothesis significance testing. This work is devoted to simulation of using popular classical
criteria of statistical hypothesis testing: Pearson’s criterion Chi-square, Fisher’s angular
transformation and Mann-Whitney U criterion. Information and communication technologies ofer
new perspectives for the analysis of the boundaries of these tests application, investigation
of the criteria sensitivity, development of approaches to statistical analysis for small samples.
Learning researches with appropriate models will be useful not only for students, but also for
researchers to improve understanding the essence of statistical data processing in pedagogic
research.</p>
      </sec>
      <sec id="sec-1-2">
        <title>1.2. Analysis of previous research</title>
        <p>
          Last time researchers pay great attention for statistical modelling as an alternative approach
to prove research hypothesises. Computer-based simulation has provided possibility to show
the boundaries of using Pearson’s criterion Chi-square at null hypothesis significance testing
(Kolgatin [
          <xref ref-type="bibr" rid="ref13">13</xref>
          ]). Computational model for investigating the eficiency of statistical hypothesis
testing was proposed. This model did not use any assumptions about probability distribution
and test features. So it could be used for comparison of methods built on diferent principles.
There was shown that Chi-square test and Fisher’s angular transformation test in the studied
range of sample sizes (from 9 to 200) do not provide good accuracy for frequency tables with 2
categories. The idea of these tests is to guarantee that we should obtain the error of the first
type (type I error) in 5 % cases (5 % significance level were used), if the null hypothesis is true.
Real value of the type I error was essentially difer within the interval from 0.04 to 0.08 instead
of 0.05. Accuracy of the type I error estimation is better (in the interval from 0.04 to 0.06), if
the sizes of samples are not less than 70. Accuracy of the type I error estimation by Chi-square
test for frequency tables with 3 categories is better even for very small samples sizes. This
accuracy essentially depends on the number of measures in samples and is worse, when one of
the sample is small and the other one is large. Therefore, some recommendations for combining
categories to use the chi-square test for small sample sizes are debatable. Another result that
was obtained in [
          <xref ref-type="bibr" rid="ref13">13</xref>
          ] is devoted to Chi-square test power, its ability to show diferences between
distributions. The type II error was quite high, it decreased with increasing the sample sizes,
when 3 categories in frequencies tables were used instead of 2 categories. This question is
discussed in this paper later in detail, but we can conclude here that this results correlate with
the statement of the American Statistical Association (ASA) about the limitations of p values
(Wasserstein and Lazar [
          <xref ref-type="bibr" rid="ref14">14</xref>
          ]).
        </p>
        <p>
          Statistical modelling as a powerful alternative to null hypothesis significance testing was
described by Lang et al. [
          <xref ref-type="bibr" rid="ref15">15</xref>
          ]. They noted that statistical modelling is a more complicated
approach than null hypothesis significance testing, but this added complexity afords researchers
the opportunity to quantify evidence in support of specific substantive hypotheses relative to
competing hypotheses — not simply against a null hypothesis [
          <xref ref-type="bibr" rid="ref15">15</xref>
          ]. The authors underlined that
the purpose of statistical modelling is to represent, as accurately and completely as possible,
a data generation process, with the goal of understanding and gathering evidence about its
structure [
          <xref ref-type="bibr" rid="ref15">15</xref>
          ]. These authors suggested and compared Bayesian and “frequentist” models for
exploring how child temperament mediates the relationship between age and developmental
progress in communication and motor skills [
          <xref ref-type="bibr" rid="ref15">15</xref>
          ].
        </p>
        <p>
          Statistical modelling as an educational tool is analysed in many scientific works. A good
review on the corresponded literature was suggested by Jamie [
          <xref ref-type="bibr" rid="ref16">16</xref>
          ]. The main idea of the
authors is to use computer simulation methods (CSMs) for the purpose of clarifying abstract
and dificult concepts and theorems of statistics. Some systems of computer mathematics
and spreadsheets are considered: SAS PROC IML, Excel, MINITAB, SAS, SPSS. There was
analysed the approaches to teach and illustrate such parts of statistical education: central
limit theorem, Student’s t-distribution, confidence intervals, binomial distribution, regression
analysis, sampling distribution, survey sampling [
          <xref ref-type="bibr" rid="ref16">16</xref>
          ].
        </p>
        <p>
          Many of the models for modelling the statistical hypothesis testing with educational purpose
was suggested at the end of last century. Flusser and Hanna [
          <xref ref-type="bibr" rid="ref17">17</xref>
          ] have used BASIC computer
programs to simulate a binomial experiment and test a simple statistical hypothesis. Taylor and
Bosch [
          <xref ref-type="bibr" rid="ref18">18</xref>
          ] suggested interactive clinical trial simulation program that provides a few thousand
simulations in about 5 minutes. Bradley et al. [
          <xref ref-type="bibr" rid="ref19">19</xref>
          ] have developed a comprehensive simulation
laboratory for statistics that could work with real experimental data from database and generate
samples according to given parameters. This software calculated p-value according F-test.
Students could see that the decisions about the null hypothesis difer for various series and
analyse the Type I and Type II errors. Ricketts and Berry [
          <xref ref-type="bibr" rid="ref20">20</xref>
          ] used statistical modelling in a
package Resampling Stats to demonstrate a histogram of Diferences between means. This
results, obtained for very small samples, helped students to understand the essence of null
hypothesis significance testing without any formulas.
        </p>
        <p>This software gave possibility to demonstrate the Type I and Type II errors for students, but
did not produce enough performance for analysing the qualities of used criteria. Therefore, it
is actual to develop some computer-based model for comparison of various approach for null
hypothesis significance testing and analysing boundaries of its using. Such model will be useful
not only for understanding the essence of null hypothesis significance testing, but it will be also
useful for understanding the limitation of the traditional null hypothesis significance testing
approach and will motivate pedagogical scientists to computational modelling as a perspective
method of statistical data analysis.</p>
      </sec>
      <sec id="sec-1-3">
        <title>1.3. Objectives</title>
        <p>We have started this work in 2014 with the objectives to use computer-based statistical modelling
for comparison and systematisation of various approaches to non-parametric null hypothesis
significance testing. The accessible for Ukrainian students information in textbooks and
handbooks was contradictory and not enough for confident and reasonable choice of the statistical
method for data analysis in pedagogical researches. We have tried to develop a statistical model
for providing learning researches with null hypothesis significance testing by university and
postgraduate students.</p>
        <p>But now we are finishing this work with the objectives to prove advantage of statistical
modelling over null hypothesis significance testing. We are grounding on our own simulations,
stormy development of information and communication technologies and newest publications
in statistical scientific literature. The aim of this research is to show the limitations of classical
null hypothesis significance testing and motivate students and researchers to computational
modelling as an efective method of research hypothesises proving.</p>
        <p>Such changing the objectives of our study leads to some inconsistency of this paper and
deprives us of opportunities to introduce this analysis directly into educational process, because
the program of statistical education should be revised taking into account obtained result. So we
can suggest our results as a matter for critical thinking and developing educational programs to
statistical educators.</p>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>2. Theoretical framework</title>
      <p>Statistical modelling of various criteria for null hypothesis significance testing needs in preparing
procedures of these criteria implementation. More over, some criteria, such as Pearson’s
Chisquare, Fisher’s angular transformation, needs data in a form of frequency table. Our model
generates the samples in metric scale, so the data should be collapsed into some intervals to
obtain the frequency table.</p>
      <p>Pearson’s Chi-square criterion was used in the form:</p>
      <p>=1 =1
 2 = ∑︁ ∑︁ (, − , )2 ,
,
(1)
(2)
where , , , – empirical and theoretical frequencies; ,  – index and number of categories;
,  – index and number of samples ( = 2 in this study).</p>
      <p>
        The form of Chi-square criterion with Yates’s correction for continuity was analysed by
D’Agostino et al. [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ], Kolgatin [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ] and was not used here. All studies in this work were
carried out for significance level of 5 %, the critical values of Chi-square criterion were assumed
according to Verma [
        <xref ref-type="bibr" rid="ref23">23</xref>
        ].
      </p>
      <p>
        The criterion of Fisher’s angular transformation was used for 2-tails in such form:
⃒
 * = 2 · ⃒⃒ arcsin
⃒
︂( 1,1 )︂
1
− arcsin
︂( 12,2 )︂ ⃒⃒⃒⃒ √︂ 1 · 2
1 + 2
where 1,1 and 1,2 – frequencies in one of the categories for samples 1 and 2; 1 and 2 –
sizes of samples 1 and 2 [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ]. The critical value of this criterion was assumed 1.96 at significance
level of 5 % (2-tail). Mostly, Fisher’s angular transformation is used for 1-sided test with critical
value 1.64 [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ]. The test power is higher in such case [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]. We used 2-sided test in this work to
have correct comparison with Pearson’s Chi-square test, which has no 1-sided form.
      </p>
      <p>
        The words “exact test” are magical for some students and even researchers. Fisher’s exact
test for consistency in a 2×2 table was analysed by D’Agostino et al. [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ], Berkson [
        <xref ref-type="bibr" rid="ref25">25</xref>
        ], Liddell
[
        <xref ref-type="bibr" rid="ref26">26</xref>
        ] etc. Their results were pessimistic. All these researchers believed that this test is exact only
because it do not use any approximations. Theoretical basis of this test is not exact, so let try
where 1, 1, 2, 2 – observed frequencies in the samples  and  in the categories 1 and 2
accordantly;  = 1 + 2 + 1 + 2 – total number of measures; 1 = 1 + 1 – number of
measures in the category 1; 2 = 2 + 2 – number of measures in the category 2;  = 1 + 2
– the size of the sample ;  = 1 + 2 – the size of the sample .
      </p>
      <p>The probability of random realisation of given combination and all other less probable
combinations is
 = * +</p>
      <p>∑︁
∀&lt;* ,∈[0;]</p>
      <p>,
 =</p>
      <p>(1)!(2)!()!()!
()!(1 − )!( − )!( −  + )!!
.</p>
      <p>
        Mann-Whitney test and its modifications are the field of researchers’ attention now and
statistical modelling is the main method of comparison the eficiency of various modifications
[
        <xref ref-type="bibr" rid="ref29 ref30">29, 30</xref>
        ]. The assumptions of this group of test were analysed by Fay and Proschan [
        <xref ref-type="bibr" rid="ref31">31</xref>
        ].
      </p>
      <p>
        Mann-Whitney test was used in our work based on research by Sidorenko [
        <xref ref-type="bibr" rid="ref32">32</xref>
        ], Gubler and
Genkin [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ], Billiet [
        <xref ref-type="bibr" rid="ref33">33</xref>
        ] in the form
our simulations to understand and illustrate the problem. We have used 2-sided form of the
Fisher’s exact test criterion, which give us the p-value (probability of the Type I error) [
        <xref ref-type="bibr" rid="ref27 ref28">27, 28</xref>
        ].
The probability of given observed frequencies combination can be calculated with the formula:
where
where
      </p>
      <p>= min(, ),
 = () +
 ( + 1)
2</p>
      <p>− ,
 = () − ,</p>
      <p>− 21 
 = √︁ (++1)
12
.</p>
      <p>
        (3)
(4)
(5)
(6)
(7)
(8)
(9)
where  and  – the sizes of  and  samples accordantly;  – the sum of ranks in the
sample . The calculated values of Mann-Whitney criterion were compared with its critical
values according the table, when both  and  were not grater than 30 [
        <xref ref-type="bibr" rid="ref33">33</xref>
        ]. Z-test for U
criterion was used in cases, where at least one of the sample size was grater than 30 [
        <xref ref-type="bibr" rid="ref33">33</xref>
        ]:
      </p>
    </sec>
    <sec id="sec-3">
      <title>3. Statistical model</title>
      <p>The method of statistical modelling was used for investigation. The model allows to form 2
samples from one population or from diferent populations that have some diferences in its
probability distributions.</p>
      <p>The first regime was used for Type I error investigation. Two series of numbers was created
on the base of the same random number generator. The values obtained were distributed into 
categories, we could control the distribution to ensure uniform distribution or the predominance
of frequencies in certain categories; an empirical value of criterion was calculated for obtained
frequencies tables and compared with the critical value of this criterion at the specified level of
significance; decision about the possibility of rejection of the null hypothesis was made. We
knew that actually the null hypothesis was true, because both samples (series of numbers) were
generated with one random number generator. But the alternative hypothesis was accepted in
some of the tests as a result of random factors. The relative frequency of such false decisions
was estimated as the probability of a type I error and should correspond to the significance level
that was used to choose critical value of a criterion.</p>
      <p>We needed a large number of trials to obtain a satisfactory precision of the analysis. 1000000
trials were conducted in computational experiments for each case. The precision of the obtained
values of the probability of a type I error was estimated on the base of the standard deviation in
consecutive identical trials. The estimated absolute error was about 0.0005 for 95 % confidence
interval. So we used all numbers with 2-3 significant digits and the last digit in all shown results
is spare guard digit. We need in a guard digit for further data processing. The number of trials
can be less in students’ investigations for saving computational time when the power of tests
are analysed. In some of the trials with very small samples were obtained zero values of the
frequencies in some categories, and it was not possible to calculate the values of a criterion.
These results were removed from the analysis, and, if their part in the total number of trials
exceeded 1 %, the study under appropriate conditions was not conducted.</p>
      <p>The second regime was used for investigation the power of the tests. Two unequal random
number generators were used to analyse of criteria sensitivity. In such case we knew that
actually the alternative hypothesis is true, because samples (series of numbers) were generated
with diferent random number generator. We could control the level of variation. The relative
frequency of true positive decisions corresponds to the criterion power that determined by the
level of diferences between the parameters of random number generators, which are used for
samples.</p>
    </sec>
    <sec id="sec-4">
      <title>4. Learning researches</title>
      <sec id="sec-4-1">
        <title>4.1. Motivation with leading questions</title>
        <p>
          One of the method to motivate students for learning research is to suggest them leading
questions after a brief theoretical review [
          <xref ref-type="bibr" rid="ref2">2</xref>
          ]. Such questions attract students’ attention to
the most problem and debatable issues of the educational content. The limitation of using
some theory, accuracy estimation, possible practical problems in specific cases are always the
problem not only for students, but also for professional researchers. Concerning to the statistical
education in using null hypothesis significance testing we would suggest students such leading
questions:
• Is Type I error fixed, when null hypothesis significance testing?
• What factors afect the power of the null hypothesis significance testing?
• Should we collapse metric scale data into some intervals?
• Which tests should we use for small samples?
• What can we know about the test power when implement null hypothesis significance
testing in practice?
• Can we prove that null hypothesis is true?
        </p>
        <p>Students find the answers on these leading questions during independent work according to
the plan of learning research. The answers can be not determined. So the process of making
conclusions is creative for students.</p>
        <p>Students should be equipped with the clear instruction for research steps and data collection.
Also, some templates for conclusions should be prepared. We’ll show the examples of tables
and diagrams as possible results of investigations. The details of instructional materials is
determined by the level of readiness of students for independent work.</p>
      </sec>
      <sec id="sec-4-2">
        <title>4.2. Learning research of the non-parametric criteria performance with true null hypothesis</title>
        <p>Now we will refer to students. You know some recommendations about limitations in using
some null hypothesis significance tests. But how important are each of these limitations? What
error can took place in each practical case of the test using. Textbooks do not give us detailed
information. We can find the answers in professional research papers, but, may be, this source of
information is not so easy to use. May be, some practical questions was not analysed in scientific
works yet. So we need to master the method of statistical modelling to explore some specific
practical problems. Study the above statistical model and use it to test non-parametric criteria
performance with true null hypothesis. This model tries to use Pearson’s Chi-square, Fisher’s
angular transformation, Fisher’s exact test for consistency in a 2×2 table, Mann-Whitney test
for testing null hypothesis for 2 samples of some given probability distribution. Both samples</p>
        <p>Templates
Accuracy of Type I error estimation with analysed tests was ?  when processing the data organised
in 2 categories
Accuracy of Type I error estimation with analysed tests ?  with increasing the sizes of
samples
The matter of the observed periodical behaviour of Type I error estimation at using Fisher’s exact test
for 2x2 frequency tables (2 categories) is ?  ℎ ℎ 
The matter of the observed periodical behaviour of Type I error estimation at using Fisher’s
angular transformation and Pearson’s Chi-square test for 2x2 frequency tables (2 categories) is
?   ℎ 
Fisher’s exact test was ?  than Fisher’s angular transformation and Pearson’s
Chisquare test for 2x2 frequency tables (2 categories)
Collapsing data of small size samples into less number of categories ? ′   improving Type I
error estimation
The observed behaviour ?  ℎ  in simulations with another probabilities distribution in
population and another sizes of samples
are the random samples from the unique population. So, the ideal test should decline the null
hypothesis in 5 % cases (Type I error on significance level 5 %). Try your simulations for given
probability distribution in population according to your individual variant and fill in the table 1.
It will be useful to create this table in some spreadsheet by copying the data from the used
Power of the analysed tests ?  with increasing the sizes of samples asymptotically
To satisfy the Type II error less than 5 % (power grater than 95 %) at using Chi-square test for 2x2
frequency tables (2 categories) we needed samples sizes  = _____ and  = _____
To satisfy the Type II error less than 5 % (power grater than 95 %) at using Chi-square test for 3x2
frequency tables (3 categories) we needed samples sizes  = _____ and  = _____
To satisfy the Type II error less than 5 % (power grater than 95 %) at using Chi-square test for 5x2
frequency tables (5 categories) we needed samples sizes  = _____ and  = _____
To satisfy the Type II error less than 5 % (power grater than 95 %) at using Fisher’s exact test for 2x2
frequency tables (2 categories) we needed samples sizes  = _____ and  = _____
To satisfy the Type II error less than 5 % (power grater than 95 %) at using Fisher’s angular
transformation test for 2x2 frequency tables (2 categories) we needed samples sizes  = _____ and  = _____
To satisfy the Type II error less than 5 % (power grater than 95 %) at using Mann-Whitney test we
needed samples sizes  = _____ and  = _____
The analysed tests can be ranged according to their power in the such order:
1. (with the most power) _____________________;
2. _____________________;
3. _____________________;
4. _____________________;
5. _____________________;
6. _____________________
1. _____________________;
2. _____________________
Power of some analysed tests can be improved in the case of one-sided hypothesis testing:
The observed behaviour ?  ℎ  in simulations with another probabilities distribution in
population and another sizes of samples
software output. Draw diagrams according to the obtained data (see the examples on figure 1
and figure 2). Analyse your results and draw conclusions according to the templates in the
table 2.</p>
      </sec>
      <sec id="sec-4-3">
        <title>4.3. Learning research of the non-parametric criteria power</title>
        <p>We continue to refer to students. Let analyse the power of the tests. You remember that,
according to the rules, we reject the null hypothesis, if the test allows us. But we never say
that we accept the null hypothesis. We should say that we can not reject it. Now we should
understand the matter of such rule. Use the null hypothesis significance test for two samples
with diferent probability distributions obtained by diferent random generators with given
diferent parameters (according to your individual variant). Store the results in the form of the
table 1. The form is the same, but now we know that null hypothesis is false. So the data in
the table will show the power of the tests. Organise your data using diagrams and show the
theoretical probability distribution in your samples, using the information about your random
generator. We have used the uniform random generators with diferent means to obtain the
examples (see figure 3, figure 4, figure 5). Analyse your results and draw conclusions according
to the templates in the table 3.</p>
        <p>As we can see, the main problem at using null hypothesis significance testing is unknown
power of tests in practical tasks. The power of tests will be low, if null hypothesis is false with
low diferences between compared populations. The tests do not give us mechanism to estimate
the power in such cases. So statistical modelling is more appropriate method of data analysing,
because the model give us possibility to estimate data distribution and confidence intervals.</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5. Conclusions</title>
      <p>Statistical model for simulation of null hypothesis significance testing has been built. Fisher’s
angular transformation, Chi-square, Mann-Whitney and Fisher’s exact tests were analysed.
Appropriate software has been developed and gave us possibility to suggest new illustrative
materials for describing the limitations of analysed tests.</p>
      <p>Learning researches in inductive statistics have been suggested on the base of statistical
modelling. This didactic materials can be useful for master and PhD students in pedagogics.</p>
      <p>Suggested methods contain new views on the use of null hypothesis significance testing. We
stress that collapsing data into less number of categories decrease the eficiency of tests and
does not give any advantage in accuracy of significance level providing.</p>
      <p>We suggest to change the accents in Ukrainian statistical education, including PhD studies,
from using null hypothesis significance testing to statistical modelling as a modern and efective
method of proving the scientific hypothesises. We ground on results of our simulations suggested
in this paper, possibilities of modern information and communication technologies, literature
review and the opinion of American Statistical Association.</p>
      <p>The field of further research is in developing the courseware for teaching the inductive
statistics based on statistical modelling. Studying the null hypothesis significance tests should
be considered as an auxiliary simplified methods.</p>
    </sec>
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