2.2: Central Tendencies Flashcards
What are the 3 measures of central tendency?
- Mean
- Median
- Mode
Mode
The most common value in a data set.
What is mode the only/best measurement for?
Nominal values
What is mode complement with?
Frequencies of each category
What is usually the value of the mode?
The absolute peak.
Discrete Variables
Variables that take on a limited number of values.
What is an example of discrete values?
Strongly agree - Strongly disagree
What do multi-modal distributions require?
Follow up analysis
- Understand what is causing the multiple peaks.
What do multiple peaks in a histogram usually mean?
There are sub groupings in the sample that need to be further analyzed.
What are the 3 questions to ask if a data set is quantitative and multimodal?
- Are there naturally occurring groups in the data that should be examined separately?
- Were there different versions of a measure used?
- Was there some procedural difference that could have created unintended groupings in the data?
Median
The middle value in a frequency distribution.
What is the point at which the median occurs?
the 50th percentile
What is the median also known as?
The ordinal middle of the distribution
Does the median use all values in the data?
NO
What data can the median be used for?
Ordinal, interval, and ratio scales
What distribution shape is best to use the median?
When the shape of the distribution for interval/ratio is skewed
Mean
The average score of a data set.
How do you calculate mean?
Sum of all data/number of data scores
What is the mean considered?
The balance point of all scores
Can you use the mean when the data is heavily skewed?
No - use the median
How many values does the mean use in the data set?
All of the values
What are 3 implications of using the mean?
- May be misleading for multi-modal data
- Misleading for heavily skewed distributions
- Influenced by extreme values
What scales is the mean best used for?
Interval and ratio scales
What shape is best to use the mean?
When the distribution for interval/ratio is symmetrical and unimodal
(normal)
When can the mode be used as the central tendency measure?
When the histogram is multimodal.
What is the only level of measurement that a symmetric histogram can be analyzed by median?
Ordinal variables
