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Kalista Cox Biostatistics Study Guide Quiz #1 - Research • collecting of information about a particular subject - MATLAB - Chapter 2: How to Summarize Data • Populations - all individuals of interest characterized by parameters • Sample - actually observed - drawn from random from the population • Levels of Measurement (variable scales) - interval (continuous) • ratio has a true 0 • ex: temperature (degrees), mmHg, days, N, m - ordinal (ranked) • numbers assigned to objects repress rank order • ex: tumor grading scale - nominal (categorical) • no arithmetic relationship between the diﬀerent classifications • ex: M/F, dead/alive • Normal/Gaussian Distribution - interval data - probability model - formula: Kalista Cox - Attributes of normal distribution • symmetric about the mean • mean=median=mode • mean and variance/standard deviation characterize the distribution • 68% of data falls between μ- and μ+ • 95% of data falls between μ-2 and μ+2 • 99% of data falls between μ-3 and μ+3 • area under normal curve between two points reflects probability - area under entire curve = 1.0 or 100% - Analyzing Interval Data • variance - mean = x_ • standard deviation of a population • standard deviation of a sample Kalista Cox • standard error of the mean - estimates whether the mean computed from a random sample estimates the true mean of the population - Population : SEM = σX Sample : = SEM sX = = σ n s n • median= 50th percentile • pth percentile= (n+1)/(100/p) observation • percentiles 2.5th percentile mean - 2 standard deviations 16th percentile mean - 1 standard deviation 25th percentile mean - 0.67 standard deviations 50th percentile (median) mean 75th percentile mean + 0.67 standard deviations 84th percentile mean + 1 standard deviation 97.5th percentile mean + 2 standard deviations • z- scores - z = (x-u)/sigma - usually equivalent to number of standard deviations from the mean • Plotting: histograms and box plots - Box Plots • IQR= Q3-Q1 • Q1= 25th percentile Kalista Cox - minimum data value within 1.5*IQR below 25th percentile • Q3 = 75th percentile - maximum data value within 1.5*IQR about 75th percentile • Checking for normal distribution - Check how well percentiles match • compare 25th to 75th and etc Name: _______________ Kalistacox ________ BME 22000 Biostatistics and Research Methods Homework #1 due 9/5/18 Use the MathWorks website (tutorials, videos, etc.) and consult Matlab Help to answer the following questions. Review course syllabus for class policy on collaborating – do your own work! 1. What is the Command Window? The window command values and variables of where is MATLAB type you such commands calculations as , equations , . 2. Name 4 types of data file formats that can be imported into Matlab. 4 of types Matlab Matlab files Text are files that formats file data . files spreadsheet , Images , into imported be can and , 3. What is the default data type for numeric data in Matlab? Matlab point floating data numeric stores - double a as precision - . 4. Briefly describe one way to view variable data in Matlab. One at view to way variable browser workspace the in data Matlab which , show will look to is to of screen your values their and variables the right the 5. What is a .mat file? A mat . such is file contains saved a as that one Matlab variables a workspace formatted data , . 6. 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