Scales of Measurement Etc Flashcards
what do scales of measurement describe?
the nature/properties of data
what are the four scales of measurement?
nominal, ordinal, interval, ratio
what does nominal scale assign?
assigns names to variables based on a particular attribute
what does nominal scale divide into what?
Divides data into discrete categories
has nominal scale quantifiable meaning?
no
has ordinal scale quantifiable meaning?
yes
what does ordinal scale report?
the ranking and ordering of data
what is assumed in ordinal scale?
intervals between values are not assumed to be equal
what is an example for ordinal scale?
likert scales
has interval scale quantifiable meaning?
yes
what is assumed in interval scale?
- intervals between values are assumed to be equal
- zero point does not assume the absence of a value
how can values not be expressed in interval scale?
values cannot be expressed as multiples or fractions
where do values not originate from in interval scale?
zero
has ratio scale quantifiable meaning?
yes
what does zero point assume in ratio scale?
the absence of a value
where do values originate from in ratio scale?
zero
how can values be expressed in ratio scale?
as multiples or fractions
short explanation of nominal
attributes are only named
short explanation of ordinal
attributes can be ordered
short explanation of interval
distance is meaningful
short explanation of ratio
absolute zero
which scales are nonparametric?
nominal and ordinal data
which scales are parametric?
interval and ratio data
what are parametric statistics?
Statistical techniques designed for use when the data have certain characteristics regarding:
* scale of measurement: Interval or ratio
* distribution: Normal
what is the advantage of parametric statistics? What use are they designed for?
parametric tests are usually more powerful
what are nonparametric statistics? What use are they designed for?
Statistical techniques designed to be used when:
* Scale of measurement: Nominal or ordinal or
* Distribution: not normal
what are descriptive statistics?
brief informational coefficients that summarize a given data set
name 3 descriptive statistics
a) Measures of central tendency
b) Measures of variability
c) Frequency distribution
what do inferential statistics allow for?
allows you to draw conclusions about your data that can be applied to the wider
population (e.g. t-test, ANOVA)
what is a variable?
A condition in an experiment or a characteristic of an entity, person, or object that can take on different
categories, levels, or values and that can be quantified (measured).
what are the properties of the mean?
- Another name for average
- Very common measure to describe the central tendency
- Is seriously affected by unusual values (outliers)
is the mean robust to outliers?
no
what are the properties of the median?
- Another name for 50th percentile
- Middle point for a data set
- Robust to outliers
what are the properties of the mode?
- The value that occurs most frequently
- One data set can have different modes
- Most useful for categorical data
what is the range?
The difference between the smallest
and largest data point
is the range robust to outliers?
no, it is highly affected by outliers
what is the standard deviation?
A measure of the variability of a set of data points around the mean
is the standard deviation robust to outliers?
no, it is sensitive to outliers
what does the standard deviation formula weigh more?
The standard deviation formula weighs unevenly spread out samples more than evenly spread samples
in which units is the standard deviation expressed in?
The standard devia6on is expressed in the same units as the original values
how to compute the standard deviation (4 steps)?
- Compute the mean
- Compute the sum of the squared difference between each data point and the mean
- Compute the variance
- Compute the square root of the variance
what does a frequency distribution describe?
the number of observations for each possible value of a variable
what is a probability distribution?
- A probability distribution is a mathematical function that describes the probability of different possible
values of a variable. - A probability distribution is an idealized frequency distribution.
It is a … distribution of what all the scores in the population would be if everyone was
tested on a particular measure
hypothetical
A probability distribution is an … frequency distribution
idealized
what are the properties of normal distribution?
- data is symmetrically distributed
- the data follows a bell shape
- most values clustering around a central region
all kinds of variables in natural and social sciences are …
normally or approximately normally distributed
what are the properties of standard normal distribution?
- Mean is 0
- Standard deviation is 1
what are the advantages of standard normal distribution?
- allows you to easily calculate the probability of certain values occurring in your distribution
- allows you to compare data sets with different means and standard deviations.
