Module 8: Descriptive Statistical Methods Flashcards
What are the 4 levels of measurement in order of lowest to highest?
- Nominal
- Ordinal
- Interval
- Ratio
Which levels of measurement are categorical and which are continuous?
Categorical: Nominal and Ordinal
Continuous: Interval and Ratio
How can the nominal level of measurement be described?
Assigning numbers to classify characteristics into categories. Categories are mutually exclusive (participants fit into only one category)
How can the ordinal level of measurement be described?
Sorting people based on their relative ranking of an an attribute.
Ex- military rank, pain scale
How can the interval level of measurement be described?
Equal numerical distance between points on a scale.
Ex- temperature, amount of money in the bank (no true zero, neg. balance)
How can the ratio level of measurement be described?
Interval level data that has a true zero.
Ex- most VS, weight, etc.
What is the goal of descriptive statistics?
To summarize and describe quantitative data
Which types of data can be averaged?
Interval and Ratio
What is used to organize raw numerical data?
Frequency distribution
In frequency distributions a set of data can be described in terms of what 3 characteristics?
- Distribution of values
- Central tendency
- Variability
Symmetric distributions are _____ _______.
mirror images
Assymmetric distributions can be ____ ____ or ____ ____
Positively skewed or negatively skewed
What is an example of data that could be positively skewed and what way does the graph’s tail face?
Tail is longer to the R
Ex- income, most people have low to moderate incomes and are at the upper end of the distribution with few people earning very high incomes
What is an example of data that could be negatively skewed and what way does the graph’s tail face?
Tail is longer to the L
Ex- age of death, most people are at the upper end of the distribution with few people dying at an early age
Modality related to distribution shapes describes:
The number of peaks
Unimodal, multimodal
What shape is a normal distribution?
Bell curve
What can the center of a normal distribution be thought of as?
The average
A single number that represents a distribution of values is known as:
central tendency
Types of central tendency include:
Mean: average
Median: midpoint when ordered numerically
Mode: most frequent
Which term describes how spread out or dispersed the data are?
Variability
What is range and why is it unstable?
The highest - the lowest score
Only used as gross descriptive index, outliers may skew
What variability index is the average amount of deviation of values from the mean and is calculated using every score?
Standard deviation (also the square root of variance)
What is standard deviation useful for?
Describing a distribution and interpreting individual scores
True or False: Assigning groups randomly is a means of providing control to a non-experimental study design?
False
What describes how far from a mean a particular score is?
Variance
