BIOS 376 Exam 1 Review Questions PDF

BIOS 376: Introduction to Biostatistics Exam 1 Review Coverage Chapter - Basic de nition - Data types (qualitative vs. quantitative - Levels of measuremen - Sampling Method - Other Terminolog Chapter - Frequency tables, relative frequenc...

BIOS 376: Introduction to Biostatistics Exam 1 Review Coverage Chapter - Basic de nition - Data types (qualitative vs. quantitative - Levels of measuremen - Sampling Method - Other Terminolog Chapter - Frequency tables, relative frequency tables, histograms, bar graphs, distribution shape Chapter - Measures of Central Tendency, Measures of Variation, Percentiles, Box-and-Whisker Plot Chapter - What is Probabilit Chapter - 6.1 Graphs of Normal Probability Distribution - 6.2 Standard Units and Areas Under the Standard Normal Distributio - 6.3 Areas Under Any Normal Curv Suggestions Make sure you are aware of terminology, notation, and procedures for solving problems To study, work through assignments, in-class problems, and problems in the text book Review the formula sheet and normal tables prior to the exam Work through your exam swiftly, but carefully If you are stumped by a question, move on to other problems and come back to it later Pay attention to the distribution of points. Check your work, if time permits. fi 1 2 3 4 6 s y s y t e ). s. n s... s  Sample Problems 1. When studying the effects of bullying in elementary schools, scientists estimated potential risk by having students complete a survey measuring their attitudes toward interpersonal violence. High scores (unit: point) correspond to a belief that, in many situations, physical force against another person is legitimate and warranted. Low scores correspond to the belief that violence is not justi ed. Consider the histogram and the ve number summary of the scores. Five number summary 5 17 25 48 92 (a) Which term best describes the shape of the distribution, based on the histogram (b) Based on the 5-number summary above, calculate the Interquartile range of the scores (c) If a score of 20 is the 40th percentile of the bullying score distribution, what percent of bullying scores are either 20 or greater than 20 2. Persons with levels of total cholesterol above 240 mg/dL are at risk for heart disease. For a particular population, the mean total cholesterol level is 170 mg/dL and the standard deviation is 30 mg/dl (a) If we assume that cholesterol levels are normally distributed, what percent of this population are at risk for heart disease? Explain your values and show your work (b) A pharmacologist aims to recruit individuals from this population with cholesterol levels between 146 and 194 mg/dL. Assuming normality, what is the probability (in decimal form) of randomly selecting an individual in this range? Show all of your work and assumptions. Use 4 places behind the decimal point fi. :. fi ?. ?.  3. An environmental health scientist is studying ozone concentrations (measured in parts per 100 million) in the air of a large US city during 18 consecutive days. Consider the following summary statistics IQR Mean Min 25th Percentile Range 2.6 4.45 1.7 2.5 8.4 (a) Find Q (b) Find the maximu 4. An industrial hygienist surveys workers in a large company to assess measures of health, safety, and comfort in their general of ce space. Provide the most likely level of measurement. One word will suf ce (a) Comfort level in general of ce area (e.g., uncomfortable, neutral, comfort-able (b) Number of work-related injuries in the past yea (c) Thermostat temperature setting in general of ce space (degree F (d) Preferred language in which to take the surve 5. A patient is told her LDL cholesterol is 140, and that this measurement is at the 10th percentile within the population. If records indicate that LDL cholesterol values are normally distributed with a standard deviation of 20, what is the mean for the population? Include units and round your nal answer to 1 place after the decimal point. 6. What type of sampling does each scenario below represent? One word will suf ce (a) A health specialist tracking infectious disease along the US-Mexico border has a station at the border checkpoint and asks every 20th person that crosses the point to complete a health survey (b) To explore the level of non-academic experience among faculty in public health, a researcher surveys all faculty members at 20 randomly selected programs in public health (c) A researcher studying the effects of national health insurance has partitioned all Arizona residents into categories of unemployed, employed full time and employed part time. She is surveying 50 people from each category fi. 3 fi : m. fi fi. fi y r ). ) fi.  (d) The state’s Department of Environmental Quality wishes to conduct a study to measure pollutants in tap water by collecting samples from 100 random households within each county in the state 7. (a) Discuss why data showing the count of all political party (e.g., republican, democrat, etc.) af liations for a large sample of the US should probably not be represented with a histogram (b) Consider a listing of blood groups for a given sample of people (i.e., O, A, B, AB). What graphic type(s) would be appropriate to present such data 8. TESAOD is a population-based prospective cohort study focusing on respiratory diseases. Below are the frequency table and barplot showing the weight information of paticipants. Normal Obese Overweight Underweight Frequency 1665 194 836 332 (a) What is the level of measurement for this variable (b) What is the relative frequency of the participants that were overweight (c) What is the mode (d) Out of a random sample of 200 people from this population, what is the probability of a randomly selected person being obese? What is your method of assigning probability here fi ?. ? ? ? ?.  9. Faculty from a chemistry department must decide which high school applicants it will accept into their program. To do this they calculate a weighted mean based on a subset of the applicants' courses. Courses in chemistry receive a weight of 4, mathematics (e.g., calculus, statistics, algebra) a weight of 3, other science courses (e.g., physics, biology, ecology) a weight of 2, and all other courses a weight of 1. Given grades from 2 students below, which will have a better chance of getting into the program based on the weighted mean? What about based on an unweighted mean? Show all of your work History Calculus Literature Chemistry Physics Statistics Student A 85 83 75 92 92 95 Student B 95 83 87 90 90 85 10. Assume that the average systolic blood pressure (SBP) for a 50-year-old woman is 125 mm Hg, with a standard deviation of 15 mm Hg, and that SBP is normally distributed. Also, hypertension is de ned as SBP > 140 mm Hg, and hypotension is de ned as SBP < 95 mm Hg. According to the empirical rule, what percentage of 50-year-old woman is (a) hypertensive (b) hypotensive (c) within the normal range of SBP 11. Find the area under the normal curve that corresponds to the following (a) area to the left of z = 1.5 (b) greater than z = -1.5 (c) area between z = -3.5 and z = -0.3 12. Birth weights in the US are normally distributed with a mean of 3420 g and a standard deviation of 495 g. If a hospital plans to set up a special intensive care room for the lightest 2.5% of babies, what weight is used for the cutoff separating the lightest 2.5% from the others ? ? fi 5 2 ? 5. fi : : ?