Lesson 1 Flashcards
Collect
E.g. Prepare a survey by composing a question and selecting a sample
Statistics
- collect
- analyze
- and draw conclusions from
…data
Analyze
E.g. Look at the results: out of a hundred people, 40 people supported your candidate. P=0.4, n=100
Conclude
E.g. We are 95% confident that the support rate lies b/w 30% and 50%
Displaying data
- individuals
- variables
Individuals
- objects described by a set of data
- 개별적인 data
Variables
- Can take different values representing diff. individuals
- let x be your lunchbox (x can be pizza, sushi, etc.)
-categorical vs. quantitative
Categorical variable
Individuals are placed into one of several categories
-categorizes all the choices u have
Quantitative variable
Takes numerical value: enabling addition, averaging, etc.
Distribution
Distribution of variable shows: what values the variable takes, frequency
- categorical: lists of categories, gives count or percent of individuals (bar graphs, pie charts)
- quantitative: dotplot, stemplot
Histogram
- large data sets involving quantitative variables
- buckets (intervals)
- stemplots retain individual data while histograms don’t
Pattern of distribution
- center, spread (variability)
- clusters/gaps (unimodal, bimodal)
- outliers
- shape: symmetry, skew, bell-shaped, uniform (right-skewed)
Frequency
- counts of each instance
- relative frequency: percents, ratios (histograms- but no frequency)
Percentile
- 내 뒤에 몇명 있나
- pth percentile is the value such that p%of observations fall below it
Time plots
Show patterns of change over time (population)
