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Exam 1 Notes Ch. 1 2 5 6

# Exam 1 Notes Ch. 1 2 5 6 - CHAPTER 1 Definitions Statistics...

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CHAPTER 1 Definitions Statistics a collection of procedures and principles for gathering data and analyzing info to help people make decisions when faced with uncertainty. Standard deviation roughly, the average difference between individual data and the mean. Rate at which something occurs, the # of times it occurs per # of opportunities for it to occur Risk of a bad outcome in the future est. by using the past rate 4 outcome assuming the future is like the past. Base risk/baseline risk: rate or risk at a beginning time period of under specific conditions. Population: collection of all individuals about which info is desired Random sample subset of the pop selected so that every ind has a specified prob of being part of sample Sample survey investigators gather opinions or other info form each ind included in sample Margin of error + or – 1/ sq. root of n. interval that is 95% certain to contain the truth about the population ex. # of individuals in sample were to be increased , the margin of error would decrease Observational study participants are merely observed and measured Variable characteristic that differs from one individual to next, numerical or categorical Confounding variable variable not main concern of study but may be partially responsible 4 observed results Randomized experiment a study which treatments are randomly assigned to participants Treatment specified regimen or procedure assigned to participants by experimenter Placebo a pill or treatment designed to look like active treatment but have no active ingredients. Statistically significant relationship or difference is one that is large enough to be UNLIKELY to have occurred in the sample if there was NO RELATIONSHIP in the population. CHAPTER 2 Q1: 25% of the values are at or below this or 75% are at or above this value Median: 50% of the values are at or below this value or 50% are at or above this value Q3: 75% of the values are at or below this value or 25% are at or above this value right skewed: hump to left of the graph & other data “tailing” to the right. Mean: greater than the median Resistance: median & IQR: less resistant to extreme observations than the mean, standard deviation, range Emperical Rule About __ of the data will be in the interval mean ± ___ (68%, s) (95%, 2 x s) (99%, 3 x s) Outlier Identifier Greater than Q3 + 1.5 × IQR, or Smaller then Q1 - 1.5 × IQR Statistic summary measure computed from sample data, parameter is a summary measure for an entire population Quantitive measurement variable, numerical variable, continuous variable Explanatory variable thought to partially explain the response variable One or Two Categorical variable: tally, cross tabulation, chi- square Pie charts single categorical variable bar graphs one or two categorical variables (2 mainly) dot plot/five number summary quantitive value QUANTITIVE Distribution:

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Exam 1 Notes Ch. 1 2 5 6 - CHAPTER 1 Definitions Statistics...

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