Descriptive Statistics Flashcards
Sample
Portion of the population
Random Sample
Sample where every element of a population has an equal chance of being selected.
Qualitative variable
non-numerical or categorical data
Quantitative variable
Numerical data
Quantitative data types
Discrete, Continuous
Discrete quantitative data
Values are finite or countable.
Continuous Quantitative Data
Any values in a line interval (measuring)
Measure Scales
Nominal, Ordinal, Interval, and Ratio Scales
Nominal Scale
Qualitative Data is placed into categories whose order is meaningless.
Ordinal Scale
Qualitative data is placed into categories whose order is meaningful but where differences cannot be determined or are meaningless.
Interval Scale
Quantitative data scale where order is representative but where there is no natural zero starting point. Differences are meaningful but ratios are meaningless.
Ratio Scale
Quantitative Data scale where order is representative and where there is a natural zero value (indicates absence of). Both differences and ratios are meaningful.
Highest level (amount) of information (scale)
Ratio Scale
What makes a frequency table complete?
Has frequency, relative frequency, and cumulative relative frequency
frequency (ni)
Number of times a value appears in a set of data
Relative Frequency (fi)
fi=ni/n
Cumulative Relative Frequency (Fi)
Fi=add previous cumulative relative frequencies.
Group values into what?
classes
Classes
Non-overlapping intervals, preferably of equal length, covering the range of observations. Classes typically include upper bound but not lower bound.
When to use data grouping
Discrete: more than 15 outcomes
or continuous quantitative data.
Bin values
Upper value for each interval
