Week 1 notes

Purdue Global University **We aren't endorsed by this school
HA 510
Aug 20, 2023
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Chapter 1 (Intro to Statistics) Descriptive: used to summarize and describe data, do not involve generalizing beyond the data at hand Inferential: converts information about the sample into intelligent guesses about the population, make conclusions Sample: small subset of a larger set of data, taken from the population Population: larger set from which the sample is drawn, who you intend to learn about Parameter: summary of information about the population Statistic: summary information about a sample Inferential statistics are based on the assumption that samples are random and represent different segments of the population Simple random sampling: every member of the population has an equal chance of selection Random assignment: randomly divided into groups Stratified sampling: used when population has a number of distinct "strata" or groups, used so all subgroups in the sample are proportional to the sizes in the population Cluster sampling: selecting a sample based on pre-organized groups Convenience sampling: selecting a sample from whatever subjects are available Variables: properties or characteristics of some event, object, or person can take on different values or amounts Independent variable: variable is manipulated by experimenter (aerobic training program) Dependent variable: effect being measured, see what happens (effect on blood pressure) Qualitative variable: those that express a qualitative attribute (hair color, religion, gender) Quantitative variable: measured in terms of numbers (height, weight, shoe size) Discrete variable: separate categories, can't be divided further; 4, 5, or 6 kids, not 4.53 kids
Continuous variable: not measured on distinct categories; 1.64 seconds, 1.645205385 seconds Percentage/percentile: 65% is the 65 th percentile Scales of measurement (NOIR) - Nominal: scale that categorizes items (male, female) - Ordinal: scale that categorizes and rank orders items (1 st , 2 nd , 3 rd place in a race) - Interval: scale that categorizes and rank orders items and has equal intervals, 0 is a point in the scale (0-temp) - Ratio: scale that categorizes and rank orders items, has equal intervals, and a 0 that means that absence or none of the thing is being measured (0-ht/wt) Descriptive statistics: - Frequency tables: method of displaying data, number of occurences for each score are listed, scores that have 0 are included - Cumulative and relative frequency: cumulative (summarizes the number of scores at or below a given score), relative/percentage (gives proportion of a given case relative to the whole data set) - Percentile rank: indicates the percentage of cases falling at or below a given score - Steam and leaf display: in between a table and a graph, contain 2 columns, left column is the first digit of the number, the right column contains the remaining digits, provides an estimation of the frequency of each score and distribution of each score - Bar graphs, histograms: bar graphs (list of scores on x-axis [horizontal], frequency on the y-axis [vertical]), histograms (used for continuous variables [bars are connected]) - Frequency curves, line graphs: formed by connecting the midpoints of all points of a histogram
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