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ASSESSMENT OF RELIABILITY OF RESEARCH RESULTS

PURPOSE OF THE LESSON. Master the parametric methods for assessing the reliability of the results of a statistical study and master the methodology for calculating the errors of average and relative values, the confidence limits of these values, the method of calculating the reliability of the difference between the average and relative values.

LESSON TECHNIQUE. Students independently prepare for a practical lesson on the recommended literature and perform individual homework. The teacher within 10 minutes checks the correctness of homework and indicates the mistakes made, checks the degree of preparation using testing and an oral survey. Then the students independently calculate the representativeness errors of the average and relative indicators, the confidence limits of the sample derived values, evaluate the reliability of the difference between the compared sample values. At the end of the lesson, the teacher checks the students' independent work.

TEST QUESTIONS:

1. What affects the reliability of statistics?

2. What is the confidence level allowed in medical research?

3. With a confidence level of 95%, what will be the value of the confidence coefficient?

4. What formula is used to determine the error of a relative indicator?

5. What formula is used to assess the significance of differences between relative values?

6. How to evaluate the reliability criterion for large and small samples?

SUMMARY OF TOPIC:

To assess the reliability of the research results means to establish the probability of the forecast with which the results of the research on the basis of the sample can be transferred to the general population or other studies. The error of representativeness (representativeness) allows one to determine the limits within which the true value of the desired parameter is found with an appropriate degree of probability of an error-free forecast, i.e. trust boundaries. Pgen = Psign ​​± tm (for relative indicators), Mgen = Msv ± tm (for average values), where Rgen and Mgen are the desired general parameters of the frequency and average level, Rvyb and Mvyb are the selected sample parameters, m is the representativeness error, t - confidence criterion. A certain degree of probability of an error-free forecast corresponds to a constant value of the confidence criterion, the value of which is determined by the table of the probability integral (for n> 30, Appendix, Table 1) or the table of the criterion t (for n <30, Appendix, Table 2). When using the table of criterion t, the number of degrees of freedom for confidence boundaries is n -1. In medical and social studies, the minimum sufficient probability of an error-free forecast is 95% (Pt = 0.95), which allows an error probability of p = 0.05. In the most critical cases, when it is necessary to draw especially important conclusions, the probability of an error-free forecast increases to 99% (Pt = 0.99, or p = 0.01) and even to 99.9% (Pt = 0.999, p = 0.001). Confidence boundaries are used not only to assess the reliability of a selective result, but also when planning in healthcare.

TASK FOR INDEPENDENT WORK:



TASK №1. Define confidence limits with a probability of an error-free forecast of 99% for relative indicators calculated from the following tasks:



Task 1

A survey of adolescents showed that out of 168 schoolchildren surveyed, 95 people rated their health status as good. Calculate the extensive metric and determine its confidence limits.

Task 2

Among 328 medical workers surveyed, 110 believe that the drug supply of medical institutions has deteriorated over the past ten years. Calculate an extensive indicator and determine its confidence limits.

Task 3.

An examination of 256 patients with hypertension in 49 revealed kidney disease. Calculate the prevalence of renal pathology in patients with hypertension and determine its confidence limits.

Task 4.

Analysis of a sample survey of 145 first-year students of the medical academy showed that professional choice was determined by personal interest in 115 people, while 30 people entered the university, following the wishes of their parents. Calculate one of the extensive indicators and determine its confidence limits.

Task 5.

An electrocardiographic study was performed on 316 patients with influenza. Changes in the cardiovascular system were detected in 72 people. Calculate the frequency of changes on the part of the heart with influenza - an intensive indicator and determine its confidence limits.

Task 6.

Of 196 patients who had myocardial infarction, 41 recurred heart attacks after a year. Calculate the recurrence rate after myocardial infarction and the confidence limits of the intensive indicator.

Task 7.

In 305 of the 950 draftees examined at the medical commission at the military registration and enlistment office, diseases restricting their fitness for military service were found. Calculate the incidence rate of draftees and the confidence limits of the intensive indicator.

Task 8.

Of the 180 stroke patients, work capacity was fully restored in 47 people. Calculate the rate of disability recovery and the confidence limits of the intensive rate.

Task 9.

A medical examination revealed that out of 260 workers who violated the diet, 98 people suffered from gastrointestinal diseases. Calculate the incidence rate of workers and the confidence limits of an intensive indicator.

Task 10.

At the end of primary school, 440 children out of 1120 students were diagnosed with myopia. Calculate the incidence of myopia in primary school students and the confidence limits of an intensive indicator.

Task 11.

An X-ray examination of 250 prisoners revealed pathological changes in the lungs in 88 people. Calculate the indicator of the frequency of pathological changes detected during fluorographic examination and the confidence limits of the intensive indicator.

Task 12.

In the district hospital of the village of Zavetnoy there are 35 beds, the average number of served population was 5890 people. Calculate the provision of rural population with stationary care and the confidence limits of the ratio indicator.

Task 13.

Of the 35 foreign students of SSMA graduates in 2004, three received a diploma with honors. Calculate the specific gravity of the excellent students and the confidence limits of the extensive indicator.

Task 14.

When studying the incidence rate of preschool children SARS, it was found that 420 registered cases of SARS diseases per 420 children. Calculate the frequency of acute respiratory viral infections among preschoolers and the confidence limits of the intensive indicator.



TASK №2. Estimate reliability of a difference of average and relative indicators



Task 1

The medical students studied the level of maximum blood pressure before and after passing the exam in pharmacology. It turned out that before passing the exam, the level of maximum blood pressure averaged 130.5 ± 5.0 mm Hg, and after passing 118.4 ± 4.1 mm Hg. Art. Is there a significant increase in student pressure before passing the exam?

Task 2

The results of a survey in Russia and Finland showed that 45.9 ± 3.2% of Russian adolescents from families of employees actively tried drugs, while in Finland this figure was 38.5 ± 4.7%. Can it be argued that adolescents in the Russian Federation reliably more often engage in drugs?

Task 3.

The proportion of women aged 15-49 who had at least one history of abortion in the Stavropol Territory was 52.6 ± 2.6, and 44.3 ± 1.8 in Ingushetia. Is it possible to say that Stavropol women reliably more often resort to abortion than in Ingushetia?

Task 4.

To assess the significance of differences between the incidence rates with temporary disability of workers in primary professions (183.7 ± 2.3%) and the incidence rates of engineering and technical workers (143.1 ± 3.3%).

Task 5.

To assess the significance of differences between the prevalence of symptoms of allergic rhinitis in primary school children of 9.7 ± 1.2% and older school age of 14.5 ± 1.4%. Is it possible to say that these indicators are significantly different?

Task 6.

To assess the significance of differences between the average annual occupancy of a bed in a city children's hospital 264.2 ± 6.2 and in a regional children's hospital 322.8 ± 4.4. Is it possible to say that these indicators are significantly different?

Task 7.

To assess the significance of differences in the average length of hospital stay of patients with cholecystitis with the use of the endoscopic method of surgical treatment (11.3 ± 0.9 days) and the laparotomy method of surgical treatment (20.5 ± 1.2 days). Is it possible to say that these indicators are significantly different?

Task 8.

The average cost of one visit to the clinic for a disease of the urinary system in 2001 was 74.3 ± 3.2 rubles, and in 2005 98.8 ± 1.7 rubles.
Is it possible to say that the average cost of one visit to the clinic for diseases of the urinary system has significantly increased?

Task 9.

To assess the reliability of the effect of radon baths and physical training on the extrasystole of patients with coronary heart disease, if the average number of ventricular extasystoles according to outpatient monitoring for 24 hours was 1443 ± 99 before treatment, and 356 ± 58 after treatment.

Task 10.

To assess the significance of the effect of the complex of therapeutic factors of the resort on the fatty acid spectrum of blood serum in patients with psoriasis, if the sum of unsaturated fatty acids in blood serum averaged before treatment 65.58 ± 1.36, and after treatment 66.28 ± 1.81 mcg / ml

Task 11.

The number of diagnostic tests performed on average per patient in day care hospitals in Stavropol amounted to 5.2 ± 0.5 in 2000 and 6.5 ± 0.7 in 2005. Can it be argued that the completeness of examination of patients in day hospitals is significantly increased?

Task 12.

Treatment of compensated chronic tonsillitis with Tonsinal in a day hospital showed an increase in the level of serum immunoglobulins, so the level of immunoglobulin G before treatment was an average of 141.2 ± 11.3, and after four-day treatment 162.3 ± 9.8. Is it possible to say that the level of general immunity after the course of treatment of chronic tonsillitis with the drug Tonsinal significantly increases?

Task 13.

Assess the significance of differences between the frequency of emergency calls for patients with coronary heart disease in the winter and spring months (in December - May, the rate of reversal was 283.2 ± 14.1 ‰) and in the summer and autumn months when the rate of reversal was 198.4 ± 10.8 ‰.

Task 14.

Assess the significance of differences in the weight of newborns if the average weight of those born in primogenous mothers was 3.350 ± 0.2 kg, and in multiparous mothers 3.72 ± 0.3 kg. Is it possible to say that these indicators are significantly different?



TASK №3. Calculate relative indicators, errors of relative indicators and determine the reliability of the difference of relative indicators

Task 1

Of 260 children of 8 years of age who played computer games for longer than 3 hours a day, visual impairment was observed in 61 children, and of 140 children of the same age who played computer games for less than 2 hours in 22 children. Is there a significant decrease in visual acuity in children with prolonged use of the computer.

Task 2

For the quarter, 158 patients with colorectal cancer were hospitalized in the abdominal department of the regional oncological clinic, including 70 under the age of 60, 88 over 60. Radical operations were performed on 102 patients, including 54 patients under the age of 60 and 48 - elderly and senile patients. Determine if there is a significant decrease in operability in elderly and senile patients.

Task 3.

The prevalence and consequences of chlamydial infection in pregnant women were studied on the basis of the Stavropol Territory Maternity Hospital. Of the 516 pregnant women, the presence of chlamydial infection was detected in 165. The threat of termination of pregnancy was observed in 75 women who did not have chlamydial infection, and 72 - suffering from this disease. Does the risk of abortion increase in the presence of chlamydial infection?

Task 4.

At the Center for Vascular Surgery of the Regional Clinical Hospital, conservative treatment of trophic ulcers of the lower extremities was performed in 35 patients, of which 12 had ulcer scarring. Surgical treatment was performed for 44 patients, for which the method of obliteration of the posterior tibial veins according to A.N. Vedensky. By the time of discharge from the hospital in 26 operated patients, the ulcers had completely healed. Is the surgical method effective in treating trophic ulcers of the lower extremities?

Task 5.

A study of the appeal of 30-40 year old men for medical help showed that out of 230 people who abuse alcohol, 27 people turned to medical facilities, and of 488 men who did not have this bad habit, 50 people turned for medical help. Is there a significant difference in the frequency of seeking medical help from 30-40 year old men who abuse alcohol and do not have this habit?

Task 6.

When analyzing industrial injuries in the rural population, it was found that 1,450 workers in agriculture account for 63 cases of injuries, including 44 cases of injuries in men (830 people) and 19 in women. Are there significant differences in injury rates in men and women?

Task 7.

The results of treating patients with cerebral palsy using a corrective suit (cosmonaut costume) showed that out of 48 patients with a hyperkinetic form, positive dynamics of the neurological status was observed in 40 children, and out of 13 patients with a hemiparetic form, there were 4. There is a significant difference in treatment effectiveness for different clinical forms of cerebral palsy?

Task 8.

Evaluate the effectiveness of medical and preventive work in a sanatorium boarding school if out of 250 students when entering the risk group (often and long-term ill with acute illnesses) 165 people were assigned, and at the end of the school year, 133 people belonged to this group, while 32 the child moved into a group of almost healthy. Is there a significant difference in the health of children before and after treatment at a boarding school?

Task 9.

Studied the prevalence of alcohol consumption in the student community. 1458 students of 1-3 courses and 1090 students of 4-6 courses were subjected to anonymous questioning. It has been established that alcohol is consumed at least once a week in junior courses by 630 students, and in older ones - 588 students. Is there a significant difference between the frequency of alcohol consumption at different stages of education?

Task 10.

Daily mortality in cerebral strokes was studied. The case histories of 98 residents of Pyatigorsk who died from cerebral strokes were analyzed, and during the time period from 2100 to 5 hours in the morning, 44 people died, in the second third of the day from 1300 to 2100 - 31 people, and in the first part of the day from 500 to 1300 23 people. Is there a significant difference in fluctuations in mortality from cerebral strokes depending on daily biorhythms?

Task 11.

Of the 360 ​​patients referred to the hospital by the ambulance and emergency room, cases of divergence of diagnoses were noted in 42 patients, and of 113 patients sent to the clinic, cases of divergence of diagnoses between the clinic and the hospital were noted in 10 patients. Is there a significant difference in the quality of diagnostics in the clinic and ambulance and emergency room?

Task 12.

Of the 63 patients in the surgical department who were operated using a plasma scalpel, a smooth postoperative course was observed in 59 people, while out of 42 patients who were operated on in the usual way, 26 did not have postoperative complications. Does using a plasma scalpel really improve treatment outcomes?

Task 13.

Finding out the level of computer literacy of doctors and nursing leaders, the following results were obtained: out of 77 doctors surveyed, 50 people own a computer, and of 29 interviewed senior nurses - 12. Is there a significant difference in the level of computer literacy of doctors and senior nurses?

Task 14.

A study of the psychoemotional state of 457 men working at a defense enterprise was carried out. Among the workers examined, 172 people smoked, and 285 did not have this bad habit. An increased level of psychoemotional stress was observed in 79 smoking workers and in 94 non-smokers. Does the level of psychoemotional stress in smoking workers reliably differ?



TASK №4. Calculate the errors of the average values ​​and evaluate the reliability of the difference between the two average indicators

Task 1

The average marriage age of 350 female students surveyed was 19.8 years, the standard deviation was 11.4, while the same indicator for 265 male students was 21.5 years, and the standard deviation was 8.6. Is the average age of marriage for students of different sexes significantly different?

Task 2

Средний уровень гемоглобина у 445 детей, получавших коровье молоко с первых месяцев жизни (до 3-х месяцев), составил 114,69 (среднеквадратическое отклонение равно 5,8). У 326 детей, получавших коровье молоко начиная с 7 месяца жизни, средний уровень гемоглобина составил 117,5, а среднеквадратическое отклонение 4,5. Достоверно ли отличается средний уровень гемоглобина у детей с разными сроками введения коровьего молока в рацион?

Задача 3.

Средняя продолжительность одного случая временной нетрудоспособности у студентов 1 курса лечебного факультета (всего 41случай ВН) составила 5,8 дней, среднеквадратической отклонение равно 2,3, тогда как у студентов стоматологического факультета средняя продолжительность одного случая временной нетрудоспособности (всего 35случаев ВН) составила 3,6 дней, а среднеквадратическое отклонение 1,9. Достоверно ли отличается средняя продолжительность одного случая временной нетрудоспособности на двух факультетах?

Задача 4.

Средний уровень успеваемости 315 студентов 6 курса лечебного факультета по дисциплине «Общественное здоровье и здравоохранение» составил 4,3 балла, среднеквадратическое отклонение равно 1,6, тогда как у 119 студентов педиатрического факультета эти показатели соответственно равны 3,9 балла и 1,1. Достоверно ли отличается уровень успеваемости выпускников на двух факультетах?

Задача 5.

Среднее число беременностей у 210 женщин 35 лет имевших самопроизвольные аборты в анамнезе составило 6,3, при этом среднеквадратическое отклонение равно 2,8, а у 432 женщин этого же возраста, не имевших самопроизвольных абортов, среднее число беременностей составило 2,9, а среднеквадратическое отклонение равно 5,4. Достоверно ли отличается число беременностей у женщин, имевших самопроизвольные аборты в анамнезе?

Задача 6.

Средний срок наблюдения за 189 пациентами с не осложненной формой острого аппендицита в стационаре составил 8,2 дня, при среднеквадратическом отклонении равном 3,1, тогда как при осложненной форме (53 чел.) длительность пребывания в стационаре увеличилась у до 11,4 дней при среднеквадратическом отклонении равном 2,2. Достоверно ли увеличивается средний срок пребывания в стационаре при осложненной форме острого аппендицита?

Задача 7.

Средний рост мальчиков 7 лет в 389 семьях со здоровым образом жизни составил 130,5см. (? =4,3), а в 59 неблагополучных по алкоголизму семьях 123,3см. (? =5,8). Достоверно ли снижение роста у детей в семьях неблагополучных по алкоголизму?

Задача 8.

Средний возраст первого сексуального опыта у 266 опрошенных городских девушек составил 15,2 года, при среднеквадратическом отклонении равном 4,8; тогда как у 150 сельских девушек он составил 16,9 лет, при среднеквадратическом отклонении равном 7,6. Имеется ли статистически достоверная разница между началом половой жизни у городских и сельских девушек?

Recommended reading:

• Лисицын Ю.П. Общественное здоровье и здравоохранение. М, 2002.

• Лисицын Ю.П. Социальная гигиена (медицина) и организация здравоохранения. Казань, 1999, с. 307 - 308

• Серенко А.Ф., Ермаков В.В. Социальная гигиена и организация здравоохранения, М, 1984, с.139 - 149.

• Юрьев В.К., Куценко Г.И. Общественное здоровье и здравоохранение. С-П, 2000, с. 197 - 199.

• Общественное здоровье и здравоохранение. Под ред. V.A. Миняева, Н.И. Вишнякова М. «МЕДпресс-информ»., 2002. – с. 108-109, 113-114.

• Зайцев В.М., Лифляндский В.Г., Маринкин В.И. Прикладная медицинская статистика. С.-П. «Фолиант», 2003.

• А.М.Мерков, Л.Е.Поляков. Санитарная статистика. «Медицина»,1974.

• Руководство по социальной гигиене и организации здравоохранения. Под редакцией Ю.П.Лисицына. М.1987.
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  10. Результаты исследования и их интерпретация
    Исследование проводилось со студентами – психологами пятого курса Новосибирского государственного педагогического университета в 2010 г. Количество испытуемых составляет 55 человек, из них 4 юноши и 51 девушка. Возраст испытуемых от 21 до 23 лет. На первом этапе исследования, целью которого являлось выявление уровня профессиональной направленности испытуемых с использованием методики Т. Д.
  11. The results of laboratory, instrumental and other special studies
    The results of general clinical, bacteriological, immunological and other studies on the days of the disease are presented. Then an assessment of their diagnostic significance is given, the degree of compliance with the preliminary
  12. Testing and implementation of research results
    Основные положения и результаты исследования обсуждались на заседаниях проблемных групп и кафедры акмеологии и психологии профессиональной деятельности Российской академии государственной службы при Президенте РФ, кафедры управления персоналом факультета социальной психологии Гуманитарного университета (г. Екатеринбург), на методологических, методических семинарах, круглых столах в МГУ им.
  13. Теоретическая значимость результатов исследования
    В результате диссертационного исследования решена важная научная проблема высшей школы в теоретическом и научно-практическом плане – формирование профессиональной компетентности у студентов и специалистов с высшим техническим образованием, которая раньше не являлась предметом самостоятельного изучения в психологии, педагогике и акмеологии. Разработана психолого-акмеологическая концепция
  14. Testing and implementation of research results
    Основные положения и результаты диссертационного исследования обсуждались на заседаниях проблемной группы и кафедры акмеологии и психологии профессиональной деятельности Российской академии государственной службы при Президенте РФ. Полученные данные апробированы автором при проведении практических занятий по курсу «Психология профессиональной деятельности». Различные аспекты диссертации,
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