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Descriptive Statistics
Published in Marcello Pagano, Kimberlee Gauvreau, Heather Mattie, Principles of Biostatistics, 2022
Marcello Pagano, Kimberlee Gauvreau, Heather Mattie
Another type of graph that can be used to summarize a set of discrete or continuous observations is the box plot. Unlike the histogram or frequency polygon, a box plot uses a single axis to display selected summaries of the measurements [45]. As an example, Figure 2.7 depicts the crude death rates for each of the 50 states and the District of Columbia in 2016, from a low of 587.1 per 100,000 population in Utah to a high of 1241.4 per 100,000 population in West Virginia [46]. (For each state, the “crude” death rate is simply the number of deaths in 2016 divided by the size of the population in that year. In Chapter 3 we will discuss this further, and investigate the differences among crudes rates, specific rates, and adjusted rates.) The central box in the box plot – which is depicted vertically in Figure 2.7 but which can also be horizontal – extends from the 25th percentile, 794.1 per 100,000, to the 75th percentile, 969.3 per 100,000. The 25th and 75th percentiles of a data set are called quartiles of the data. The line running between the quartiles at 891.6 deaths per 100,000 population marks the 50th percentile of the data set; half the observations are less than or equal to 891.6 per 100,000, and the other half are greater than or equal to this value. If the 50th percentile lies approximately halfway between the two quartiles, this implies that the observations in the center of the data set are roughly symmetric.
Basic stats
Published in O. Ajetunmobi, Making Sense of Critical Appraisal, 2021
The ‘interquartile range’ (IQR) is a statistical measure describing the extent of spread of the middle 50% of ranked data. IQR is commonly used alongside a median value when describing the spread of skewed data. As illustrated below, three quartiles (lower, median and upper quartiles) are used to divide ranked data into four equal parts (Figure 1.2).
Exposure–Response Analysis in Oncology Trials
Published in Satrajit Roychoudhury, Soumi Lahiri, Statistical Approaches in Oncology Clinical Development, 2018
Yi-Lin Chiu, Balakrishna S. Hosmane
We simulated all six cases for EACRM (LN1-LN3, W1-W3), two cases for EACRM without weights (LN0 and W0), as well as the 3 + 3 design (3 + 3) under both 120-mg and 70-mg targeted doses. The summary statistics are listed in Table 3.10 for 120-mg targeted dose. The 25%, 50%, and 75% label denotes the corresponding quartiles of the distribution of variables including the median.
Years of dermatology experience and geographic region are associated with outlier performance of excision or destruction for nonmelanoma skin cancer
Published in Journal of Dermatological Treatment, 2023
Brad R. Woodie, Scott A. Neltner, Annabella G. Pauley, Alan B. Fleischer
This study analyzed dermatologists’ use of excisions and destructions to treat NMSC in the Medicare population. Dermatologists practicing in the Northeast performed more destruction and less excision than those in the Midwest, West, and South. Outlier performance of destructions was also more likely in the Northeast. Outlier status for excisions, defined here as exclusive performance of excision, was more likely for dermatologists in the Midwest, West, and South. With respect to RUCA code, this study suggests that urban or rural status may not be associated with NMSC treatment modality. This study also suggests that income of the practice zip code does not impact treatment choice if those performing an above average proportion of excisions are grouped with excision outliers. When looking at outliers, we saw that higher income quartiles had more exclusive performance of excision or destruction.
Frequency and clinical significance of histologic upper gastrointestinal tract findings in children with inflammatory bowel disease
Published in Scandinavian Journal of Gastroenterology, 2022
Marleena Repo, Johanna Pessi, Eelis Wirtanen, Pauliina Hiltunen, Heini Huhtala, Laura Kivelä, Kalle Kurppa
Clinical characteristics and prevalence of abnormal laboratory values or histopathological findings are presented as percentage distributions. The skewness of quantitative variables was assessed by the Shapiro-Wilk method and most of the variables were not normally distributed. Thus, for the sake of simplicity, all quantitative data is expressed as medians with lower and upper quartiles. Chi-squared test or Fisher’s exact test were used to compare the qualitative variables between the groups. Laboratory values between groups were compared using the Kruskal-Wallis one-way analysis of variance or by Fisher’s exact test. The association between clinical features and presence of UGI findings was analyzed by binary logistic regression analysis and presented with odds ratios (OR) with 95% confidence intervals (CI). p values ≤.05 were considered statistically significant. All the statistical analyses were performed using SPSS Statistics version 25 (IBM Corp, Armonk, NY, USA).
Foetal umbilical cord brain-derived neurotrophic factor (BDNF) levels in pregnancy with gestational diabetes mellitus
Published in Journal of Obstetrics and Gynaecology, 2022
Melike Geyik Bayman, Zeynep Ozturk Inal, Fatih Hayiroglu, Elif Nur Yildirim Ozturk, Kazim Gezginc
All data analyses were performed using SPSS (Statistical Packages for The Social Sciences) software, version 21 (SPSS Inc. Chicago, USA). The Kolmogorov-Smirnov test was used to test for normal or abnormal distributions of the continuous variables. An independent samples T-test was used for the between-group comparisons of the continuous variables with normal distributions. The data are expressed as mean ± SD. The Mann-Whitney U test was applied for variables with a non-normal distribution. The data are expressed as median and inter-quartile ranges. Categorical data were analysed by Pearson’s Chi-square test, and Fisher’s exact test was applied if the expected frequency was less than 5 in >20% of all cells. A p-value of less than 0.05 was accepted as statistically significant.