Chapter 2 Graphical Descriptive Techniques 1 Flashcards
What is a variable
Some characteristic of a population or sample. Usually represented using X, Y, Z
What are the values of the variable
The possible observations of the variable (the range of possibilities, ex. the values of a statistics exam marks are the integers between 0 and 100)
What is Data
The observed values of a variable
What is the singular word for data
Datum (Ex. The mark of one student is a datum)
What are the three types of data?
Interval, nominal and ordinal
What two data types are combined for the purposes of statistics
Ratio and Interval data
What is interval data?
Real numbers such as:
Heights, weights, incomes and distances
What is interval data also referred to as?
Quantitative or numerical data
What is nominal data?
The value of nominal data are categories
Usually represented by numbers attached to a category
1 = Single
2 = Married
3 = Divorced
What is nominal data also referred to as?
Qualitative or categorical data
What is ordinal data
Appears to be nominal, however in ordinal data the order of values has meaning (Ex. rating systems ranging from 1-5, etc.)W
Can the order from ordinal data help you determine differences between the ranks
No, since the ranking only gives information about the ranking and does not give any other type of information to calculate differences.
Name the three types of data and what calculations are permitted on them
Interval Data: all calculations
Nominal Data: no calculations, only thing permitted is to count or computer the percentages of the occurrences of each category
Ordinal Data: only permissible calculations are those involving a ranking process (Ex. calculation of a median)
List out the Hierarchy of Data for the three data types
Interval:
Values are real numbers
All calculations are valid
Data may be treated as ordinal or nominal
Ordinal:
Values must represent the ranked order of the data
Calculations based on an ordering process are valid
Data may be treated as nominal but not as interval
Nominal
Values are the arbitrary numbers that represent categories
Only calculations based on the frequencies or percentages of occurrence are valid.
Data may not be treated as ordinal or interval
Explain the Hierarchy of Data and what changes between data are allowed, as well as their effect on the quality of the information
Interval
Ordinal
Nominal
A data type can be represented as a data type below itself, however it can no be represented by a data type above itself.
In the transfer below data types, information is lost.
Example:
A mark of 62 at school is interval data
That same mark can be represented by a letter grade (however that letter grade has a greater range therefore the more accurate measurement of the mark is lost)
That mark can be determined to be either a pass or fail which would be a nominal data type, further causing more loss of information
