GRAVETTER_CH03_SELECTING A MEASURE OF CENTRAL TENDENCY Flashcards
REVIEW! What is the goal of central tendency?
The goal of central tendency is to find the single value that best represents the entire distribution.
TRUE OR FALSE: We should note that whenever the scores are numerical values (interval or ratio sale), the mode is usually the preferred measure of central tendency.
FALSE.
It’s the mean!
THINK! Why is the median the preferred measure of central tendency when extreme scores exist?
This is the case, because extreme values offset or distort the mean, so the mean does not become very representative of the frequency distribution.
The median, however, is not easily affected by extreme scores.
TRUE OR FALSE: The median is useful when working with undetermined values in a dataset.
TRUE.
The experimenter cannot discard the score or assign a value to it, as it will violate the goal of central tendency. They cannot use the mean either, since it is impossible due to the undetermined value. In the end, however, this undetermined value is a score, and by that virtue, the median can still be determined. (e.g. 3 scores are below the median, and 3 scores, including the undetermined value, are above the median)
What is a term for a distribution with no upper limit (or lower limit) for one of the categories? e.g. “5 or more”
Open-ended.
THINK! Why is the median usually the preferred measure of central tendency for an ordinal scale?
The median is defined by direction (half of the scores are above the median and half are blow the median), and ordinal measurements allow us to determine direction (greater than or less than).
The mean, meanwhile is defined in terms of distances, and because ordinal scales do not measure distance, it is not appropriate to compute a mean for scores from an ordinal scale.
What measure of central tendency is used when reporting the average value for a skewed distribution?
The median. This is because the median is relatively unaffected by extreme scores.
TRUE OR FALSE: It is possible to compute for the mean with an open-ended distribution.
FALSE.
Because of the open-ended distribution or category, you cannot find the sum of scores. However, you can still find the median.
TRUE OR FALSE: The mode can be used as an alternative to the mean, or is used in conjunction with the mean to describe central tendency.
TRUE.
TRUE OR FALSE: The mode is the only option for describing central tendency for nominal data.
TRUE.
It is impossible to compute a mean or a median for data from a nominal scale.
THINK! Although discrete variables are numerical and capable of producing a mean, why is the mean not sensible for discrete variables, and why is the mode more preferrable?
The mean often produces values that are fractional, and discrete variables are not often fractional (e.g. there is no such thing as 2.5 children). In many situations such as this, the mode is more preferable because the value this presents is more realistic.
TRUE OR FALSE: It is customary that the independent variable is on the x-axis of a graph while the dependent variable is on the y-axis of a graph.
TRUE.
TRUE OR FALSE: Line graphs and histograms are used when the values on the horizontal axis are measured on an interval and ratio scale, while bar graphs are used when the values are of a nominal and ordinal scale.
TRUE.
