scholarly journals Explorations in statistics: the assumption of normality

2017 ◽  
Vol 41 (3) ◽  
pp. 449-453 ◽  
Author(s):  
Douglas Curran-Everett
Keyword(s):  
Normal Distribution ◽  
T Test ◽  
Theoretical Distribution ◽  
Sample Mean ◽  
Quantile Plots ◽  
The Difference

Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This twelfth installment of Explorations in Statistics explores the assumption of normality, an assumption essential to the meaningful interpretation of a t test. Although the data themselves can be consistent with a normal distribution, they need not be. Instead, it is the theoretical distribution of the sample mean or the theoretical distribution of the difference between sample means that must be roughly normal. The most versatile approach to assess normality is to bootstrap the sample mean, the difference between sample means, or t itself. We can then assess whether the distributions of these bootstrap statistics are consistent with a normal distribution by studying their normal quantile plots. If we suspect that an inference we make from a t test may not be justified—if we suspect that the theoretical distribution of the sample mean or the theoretical distribution of the difference between sample means is not normal—then we can use a permutation method to analyze our data.

scholarly journals COMPARACION DEL PROMEDIO Y LA MEDIANA COMO ESTIMADORES DE LA MEDIA PARA MUESTRAS NORMALES DEPENDIENDO DEL TAMAÑO DE MUESTRA

2017 ◽  
Vol 23 (2) ◽  
pp. 33
Author(s):  
José W. Camero Jiménez ◽  
Jahaziel G. Ponce Sánchez
Keyword(s):  
Confidence Interval ◽  
Sample Size ◽  
Normal Distribution ◽  
Confidence Intervals ◽  
Hypothesis Tests ◽  
Sample Mean ◽  
Palabras Clave ◽  
The Mean ◽  
The Difference

Actualmente los métodos para estimar la media son los basados en el intervalo de confianza del promedio o media muestral. Este trabajo pretende ayudar a escoger el estimador (promedio o mediana) a usar dependiendo del tamaño de muestra. Para esto se han generado, vía simulación en excel, muestras con distribución normal y sus intervalos de confianza para ambos estimadores, y mediante pruebas de hipótesis para la diferencia de proporciones se demostrará que método es mejor dependiendo del tamaño de muestra. Palabras clave.-Tamaño de muestra, Intervalo de confianza, Promedio, Mediana. ABSTRACTCurrently the methods for estimating the mean are those based on the confidence interval of the average or sample mean. This paper aims to help you choose the estimator (average or median) to use depending on the sample size. For this we have generated, via simulation in EXCEL, samples with normal distribution and confidence intervals for both estimators, and by hypothesis tests for the difference of proportions show that method is better depending on the sample size. Keywords.-Sampling size, Confidence interval, Average, Median.

Retail Mix Dan Kepuasan Konsumen Minimarket

Liquidity ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 53-62
Author(s):  
Siti Maryama ◽  
Yayat Sujatna
Keyword(s):  
Consumer Satisfaction ◽  
Quantitative Method ◽  
Descriptive Analysis ◽  
T Test ◽  
Primary Data ◽  
Retail Industry ◽  
Location Data ◽  
Store Design ◽  
Customer Services ◽  
The Difference

The purpose of this study is to (1) analyzing the level of retail mix consumer satisfaction; (2) analyze the dominant variable in retail mix consumer satisfaction; (3) analyze the difference of retail mix consumer satisfaction performed. The observed of the retail industry is Alfamidi and Indomaret. The study was designed into a descriptive-quantitative method. The source of primary data obtained from the questionnaire of 100 respondents. The formulating variable of retail mix includes: merchandise assortments, pricing, customer services Store design and display, communication mix, and location. Data analyze by using descriptive, analysis of factors, and t-test. The result confirmed that the level of retail mix consumer satisfaction in both industry is relatively similar. However, it can be stated that the respondents were more satisfied to Indomaret compared with Alfamart.

Perbedaan Metode Three Compartement Sink dengan Air Panas dan Larutan Klorin terhadap Angka Kuman Alat Makan di RSU Queen Latifa

2017 ◽  
Vol 19 (2) ◽  
pp. 126-130
Author(s):  
Rifatun Hasanah ◽  
Setyowati Setyowati ◽  
Noor Tifauzah
Keyword(s):  
Infectious Diseases ◽  
Confidence Level ◽  
Disease Transmission ◽  
T Test ◽  
Hot Water ◽  
Independent Test ◽  
The Difference ◽  
Hospital Use

Background:One of the efforts in preventing congenital food disease is by washing the cutlery perfectly. The cutlery used by patients with infectious diseases should be noted more, because it has a risk in disease transmission through cutlery. The process of washing the cutlery for infected patients in Queen Latifa Hospital use three compartement sink method with hot water, while the three compartement sink method with clorine solvent has never been tested. Purpose: Research was to determine the difference in the number of germs in the tool was washed using three compartement sink method with hot water and with clorine solvent. Method:Types of research is experiment with rancangan percobaan acak kelompok (RAK). The object of this research is 4 plates and 4 bowls. The number of experimental units in this research were 2 treatments x 2 cutlery x 2 checks x 2 reapetitions = 16 experimental units. The analysis used independent t-test with 95% confidence level. Result :The average number of germs in the cutlery washed using the three compartment sink method with hot water was 1 x 101 cfu / cm2, whereas with chlorine solvent is 0.2 cfu / cm2. Independent test t-test shows p = 0.049 which means the hypothesis is accepted. onclusion : There are differences in the number of germs in the washing cutlery using the three compartment sink method with hot water and with chlorine solvent.   Keywords: number of germs, cutlery, three compartment sink

Perbedaan Metode Three Compartement Sink dengan Air Panas dan Larutan Klorin terhadap Angka Kuman Alat Makan di RSU Queen Latifa

2017 ◽  
Vol 19 (2) ◽  
pp. 126
Author(s):  
Rifatun Hasanah ◽  
Setyowati Setyowati ◽  
Noor Tifauzah
Keyword(s):  
Infectious Diseases ◽  
Confidence Level ◽  
Disease Transmission ◽  
T Test ◽  
Hot Water ◽  
Independent Test ◽  
The Difference ◽  
Hospital Use

Background:One of the efforts in preventing congenital food disease is by washing the cutlery perfectly. The cutlery used by patients with infectious diseases should be noted more, because it has a risk in disease transmission through cutlery. The process of washing the cutlery for infected patients in Queen Latifa Hospital use three compartement sink method with hot water, while the three compartement sink method with clorine solvent has never been tested. Purpose: Research was to determine the difference in the number of germs in the tool was washed using three compartement sink method with hot water and with clorine solvent. Method:Types of research is experiment with rancangan percobaan acak kelompok (RAK). The object of this research is 4 plates and 4 bowls. The number of experimental units in this research were 2 treatments x 2 cutlery x 2 checks x 2 reapetitions = 16 experimental units. The analysis used independent t-test with 95% confidence level. Result :The average number of germs in the cutlery washed using the three compartment sink method with hot water was 1 x 101 cfu / cm2, whereas with chlorine solvent is 0.2 cfu / cm2. Independent test t-test shows p = 0.049 which means the hypothesis is accepted. Conclusion : There are differences in the number of germs in the washing cutlery using the three compartment sink method with hot water and with chlorine solvent.

Effect of smoking on cardiovascular autonomic functions

2021 ◽  
Vol 9 (2) ◽  
pp. 3780-3784
Author(s):  
P.Vani ◽  
◽  
Sharan B Singh M ◽  
Keyword(s):  
Heart Rate ◽  
Autonomic Function ◽  
T Test ◽  
Resting Heart Rate ◽  
Autonomic Functions ◽  
Mean Values ◽  
Function Tests ◽  
Significant Difference ◽  
The Mean ◽  
The Difference

Introduction: Cigarette smoking is a prime risk factor for cardiovascular morbidity and mortality. Chronic smoking results in autonomic dysfunction leading to increased cardiovascular risk in smokers. The present study was planned to study the effect of smoking on the Cardiovascular Autonomic Functions among smokers. Materials and Methods: Fifty male subjects who were in the age group of 25 to 45 years. They were grouped into 25 smokers and 25 non-smokers. The participant subjects were selected among the staff members, residents and the patients from the routine OPD in SVIMS. Prior to study, they were informed about the procedure and the purpose of the study tests and written consents were obtained from them. The Cardiovascular Autonomic Function Tests were assessed by using a POLYGRAPH which was available in the department. Results and Conclusion: After applying the ‘t’-test for the difference between the two sample means, it was observed that there was a highly significant difference between the mean values of the BMI(i.e.p<0.01) and the para-sympathetic function tests among the smokers and the non – smokers(i.e.p<0.00). The Resting Heart Rate had significantly increased and the Deep breathing difference, the postural tachycardial index (Response to standing) and the Valsalva Ratio had significantly decreased in the smokers as compared to those in the non – smokers. After applying the ‘t’-test for the difference between the two sample means, it was observed that there was no significant difference between the mean values of the Postural hypotension test (i.e. p>0.05) and that there was a highly significant difference between the mean values of the Sustained handgrip test in the smokers and the non – smokers (i.e. p<0.00). KEY WORDS: Cardiovascular autonomic function tests, Smoking, Resting heart rate.

scholarly journals Image Anomaly Detection Using Normal Data Only by Latent Space Resampling

2020 ◽  
Vol 10 (23) ◽  
pp. 8660
Author(s):  
Lu Wang ◽  
Dongkai Zhang ◽  
Jiahao Guo ◽  
Yuexing Han
Keyword(s):  
Anomaly Detection ◽  
Normal Distribution ◽  
Autoregressive Model ◽  
Probability Model ◽  
Latent Space ◽  
Industrial Inspection ◽  
Detection Stage ◽  
Novel Method ◽  
The Difference ◽  
Reconstruction Model

Detecting image anomalies automatically in industrial scenarios can improve economic efficiency, but the scarcity of anomalous samples increases the challenge of the task. Recently, autoencoder has been widely used in image anomaly detection without using anomalous images during training. However, it is hard to determine the proper dimensionality of the latent space, and it often leads to unwanted reconstructions of the anomalous parts. To solve this problem, we propose a novel method based on the autoencoder. In this method, the latent space of the autoencoder is estimated using a discrete probability model. With the estimated probability model, the anomalous components in the latent space can be well excluded and undesirable reconstruction of the anomalous parts can be avoided. Specifically, we first adopt VQ-VAE as the reconstruction model to get a discrete latent space of normal samples. Then, PixelSail, a deep autoregressive model, is used to estimate the probability model of the discrete latent space. In the detection stage, the autoregressive model will determine the parts that deviate from the normal distribution in the input latent space. Then, the deviation code will be resampled from the normal distribution and decoded to yield a restored image, which is closest to the anomaly input. The anomaly is then detected by comparing the difference between the restored image and the anomaly image. Our proposed method is evaluated on the high-resolution industrial inspection image datasets MVTec AD which consist of 15 categories. The results show that the AUROC of the model improves by 15% over autoencoder and also yields competitive performance compared with state-of-the-art methods.

scholarly journals Adjustment among Private and Government Nursing College’s Girl Students Who Studding from Home and Hostel

2017 ◽  
Vol 5 (1) ◽  
Author(s):  
Nitesh N. Patel
Keyword(s):  
Private Sector ◽  
Stress Level ◽  
T Test ◽  
Stress Scale ◽  
Significant Difference ◽  
Correlation Result ◽  
The Difference ◽  
Girl Students

The present investigation to find out the difference of adjustment between girl students of nursing living in home and hostel. The sample constructed of 160 girl students of nursing, out of which 80 girl students of nursing living in home, 60 from girl students of nursing living in hostel for this purpose of investigation. Adjustment stress scale Bell Adjustment Inventory (BIQ) was administered to measure their adjustment stress level. Scoring has been done as per manual. The data was analyzed by statistical ‘t’ test and correlation. Result was found that, there is significant difference in level of adjustment between girl students of nursing living in home and hostel. There is more adjustment level in the girl students of nursing who living in home then living in hostel. It was also found that, there is no significant difference between level of adjustment between private sector and government sector’s girl students of nursing.

scholarly journals Effects of Negative Emotions on Cognitive Schemas

2020 ◽  
Vol 11 (1) ◽  
pp. 65-69
Author(s):  
Marius-Gabriel Amzulescu ◽  
Andreea-Ionela Chiscop ◽  
Diana-Nicol Marin ◽  
Cristina Lare ◽  
Andra-Maria Popescu
Keyword(s):  
Negative Emotions ◽  
T Test ◽  
Control Group ◽  
Core Beliefs ◽  
Cognitive Schemas ◽  
Main Research ◽  
Significant Difference ◽  
Independent Variable ◽  
The Difference ◽  
The University

The present study investigates the effect of negative emotions (focusing on disappointment, sadness and regret) on cognitive schemas. The sample consist in students from the University of Bucharest (convenience groups). A univariate unifactorial experimental design was used, as the current study had one independent variable, negative emotions, and a dependent variable, cognitive schemas, which was measured with the Core Beliefs Questionnaire instrument. We applied T test for independent samples, using SPSS. The t test was statistically significant, t (45) = 2.57, p <0.05. The confidence interval (95%) for the difference between the averages is between 2.95 and 24.35. After applying the intervention, the evaluated sample (M = 43.17, SD = 29,074) showed a statistically significant difference compared to the control group (M = 29.52, SD = 11.257). The data collected support the main research hypothesis of the study, negative emotions can bring about changes in certain cognitive schemas by modifying, altering or disrupting them.

scholarly journals PSX-35 Late-Breaking Abstract: Use of total tract NDF and starch digestibility in beef cow and replacement heifer diet formulation

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 354-354
Author(s):  
Garland Dahlke ◽  
Devin Jakub ◽  
John Goeser ◽  
Erika L Lundy
Keyword(s):  
T Test ◽  
Neutral Detergent Fiber ◽  
Starch Digestibility ◽  
Energy Estimates ◽  
Actual Performance ◽  
Average Bias ◽  
Beef Cow ◽  
Commercial Laboratory ◽  
Diet Formulation ◽  
The Difference

Abstract The objective of this trial was to evaluate the effectiveness of using the total tract neutral detergent fiber (TTNDFd) and starch digestibility methodology in the formulation of beef cow and replacement heifer rations. This methodology ultimately applies to the estimation of energy availability to the animal and accompanied performance as outlined by the NASEM 2016 Nutrient Requirements of Beef Cattle publication. Multiparous, Angus cows during the last two months of gestation and yearling replacement, Shorthorn heifers comprised the study. Cows received one of four, dry ingredient diets while heifers received a corn silage-based diet. Feed nutrient evaluation along with intake were documented and applied to the NASEM model for these cattle. Results were compared to actual performance. Acid detergent fiber (ADF) derived energy estimates which generally accompany commercial laboratory feed analysis reports were compared as well. A T-test between actual and projected growth was used to describe the difference. The T-test between the TTNDFd/Starch derived results did not show any statistical difference between the actual and projected results for heifers P(T&lt; =t) 0.15 with an average ADG bias of -0.06 Kg. The cow results over the four diets P(T&lt; =t) ranged from 0.41 to 0.004 with an average bias of 0.04 to 0.27 Kg overestimating ADG. The T-test between the ADF derived results showed a difference between the actual and estimated values for heifers P(T&lt; =t) 0.0004 with an average ADG bias of 0.2 Kg. The cow results over the four diets likewise over estimated available energy substantially. Here the test ranged from P(T&lt; =t) 0.03 to 0.0001 with an average bias of 0.35 to 0.7 Kg. It appears that TTNDFd methodology should be strongly considered in the evaluation of forages and in the development of ration formulation software for beef offered high levels of fiber in their ration.

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