Measurement Flashcards
Statistic
characteristic of a sample
denoted with English letters (X, s)
Parameter
characteristic of a population
denoted using Greek letters (μ, σ)
Order of operations
- Brackets
- Exponents
- Multiplication
- Summation
- Addition or subtraction
5 eg, ∑ Xi + 3 i=3 summation --> X3 + X4 + X5 = sum then addition --> sum + 3
Nominal scale
NAMES
categories with no particular order (no rank or magnitude relationships between them)
eg. gender, eye colour, religion, etc.
Ordinal scale
RANK ORDER
intervals between ranks are not necessarily equal in size
eg. ranking in a contest (1st, 2nd, 3rd place), anxiety level (none, low, moderate, high)
Interval scale
NO ABSOLUTE ZERO POINT
intervals between scores are equal in size
numbers represent ranks and magnitudes
eg. calendar year (1999, 2022), temperature (F or C)
Ratio scale
ABSOLUTE ZERO POINT
intervals between scores are equal in size
numbers represent ranks and magnitudes
eg. years elapsed since the big bang, temperature (Kelvin), age, dollars, reaction time
Scale for qualitative/categorical variables
Nominal
Scales for quantitative variables
Ordinal
Interval
Ratio
Scale used for psychological scales
Interval
Discrete variables
no possible values in between units
– number of … (children, coin flips, touchdowns)
Continuous variables
infinite possible values in between units
– height, weight, amount of … (water, time)
Bar graph
for nominal and ordinal data
spaces between the bars
eg undergrad major (x-axis), number of students (y-axis)
Histogram
divides up the range of possible values in a data set into classes or groups
for interval and ratio data
symmetrical or skewed
Skew
demonstrated on a bell curve when data points are not distributed symmetrically
Positive skew: right skew
Negative skew: left skew
