Continuous variable
A quantitative variable that can assume any value over a certain interval or intervals
Cross section data
Data collected on different elements at the same point in time for the same period of time
Data set
Collection of data on the elements of a population or sample
Descriptive statistics
Collection of methods for organizing, displaying, and describing data using tables, graphs, and summary measures
Discrete variable
A quantitative variable whose values are countable
Element
A specific subject or object included in a sample or population about which information is collected
Inferential statistics
Collection of methods that help make decisions about a population based on sample results
Observation
The value of a variable for an element
Population
The collection of all elements whose characteristics are being studied.
Qualitative variable
A variable that cannot assume numerical values but is classified into two or more categories
Quantitative variable
A variable that can be measured numerically
Random sample
A sample drawn in such a way that each element of the population has some chance of being included in the sample
Representative sample
A sample that represents the characteristics of a population as closely as possible
Sample
A portion of the population selected for study
Statistics
Group of methods used to collect, analyze, present, and interpret data to make decisions
Time series data
Data collected on the same element for the same variable at different points in time or for different periods of time
Variable
A characteristic under study that assumes different values for different elements
Mean, median, mode, range, percentile, quartile, etc.
Descriptive statistics
Use a ____ when the difference between the highest and lowest frequencies is "small" compared to overall data
Truncation
The calculate degree of pie chart "slice
(Relative frequency)(360)
Relative frequency
Frequency of element/sum of all frequencies
Class width
Difference between consecutive lower limits or consecutive upper limits
(Highest value-lowest value)/# of classes
Approx class width
Connect the midpoints of the tops of the bars on a histogram and start and stop on the x axis
Polygon
All frequencies are equal
Uniform
Left half mirrors the right half
Symmetric
Has left or right "tail
Skewed
Tail goes the the right
Skewed right
Halfway between one upper limit and the next lower limit of normal classes
Boundary
Money
Continuous
Steam and leaf; left side
Steam; tens value
Steam and leaf; right side
Leaf; ones value
Measures of central tendency for ungrouped data
Mean, mode, and median
Four or more modes
Multimodal
3 modes
Trimodal
2 modes
Bimodal
Means are ____ influenced by outliers
Highly
Modes are ____ influenced by outliers
Not
Medians are ___ effected by outliers
Hardly
Measures of dispersion for ungrouped data
Range, variance, and standard deviation
Uses of standard deviation
Chebyshev's Theorem and Empirical Rule o
If a data set is bell shaped then approx ___% of data is within one standard deviation of the mean
68
If the data set is bell shaped then approximately __% of the data is within 2 standard deviations of the mean
95
If the data set is bell shaped then approximately __% of the data is within 3 standard deviations of the mean
99.7
Measures of position
Median, quartiles, and percentiles
Percentile rank
#values less than/#values all together
Three numbers that divide a data set into quarters (roughly)
Quartiles