ia.Statistics Class
Provides statistical information about an array of numbers (data).
Constructor
ia.Statistics
-
data
Parameters:
-
dataNumberAn array of numbers.
Item Index
Methods
_invalidateData
()
private
Called when the data has been changed to recalculate statistics.
getData
-
the
Gets the data array.
Parameters:
-
theNumberarray.
getPercentile
-
percentile -
a
Returns the percentile at the given position in the dataset. Uses the sorted array.
Parameters:
-
percentileNumberValid values are 0 to 1.
- Q1 (Lower Quartile): The 25th percentile (0.25).
- Q2 (Median): The 50th percentile (0.5).
- Q3 (Upper Quartile): The 75th percentile (0.75).
-
aNumberThe array of numbers to use - sorted or unique.
Returns:
setData
-
data
Sets the data array.
Parameters:
-
dataNumberthe array.
statsToString
()
String
Get a simple text representation of the main statistics.
Returns:
toString
()
String
Get a simple text representation of this object.
Returns:
Properties
interquartileRange
Number
The interquartile range.
lowerQuartile
Number
The lower quartile.
maxValue
Number
The maximum value.
mean
Number
The average value of the dataset, i.e. the sum of all the data divided by the number of variables. The arithmetic mean is commonly called the "average". When the word "mean" is used without a modifier, it usually refers to the arithmetic mean.
The mean is a good measure of central tendency for symmetrical (e.g. normal) distributions but can be misleading in skewed distributions since it is influenced by outliers. In general, the mean is larger than the median in positively skewed distributions and less than the median in negatively skewed distributions.
Therefore, other statistics such as the median may be more informative for distributions that are frequently very skewed. The mean, median, and mode are equal in symmetrical frequency distributions. The mean is higher than the median in positively (right) skewed distributions and lower than the median in negatively (left) skewed distributions.
median
Number
The middle value in the dataset, i.e. half the variables have values greater than the median and the other half values which are less. The median is less sensitive to outliers (extreme scores) than the mean and thus a better measure than the mean for highly skewed distributions.
minValue
Number
The minimum value.
mode
Number
The most frequently occurring value in the dataset. Easy to determine, but subject to variation and of limited value.
modeCount
Number
The number of occurrences of the mode value
modeString
Number
The difference between the largest and the smallest value in the dataset. Since the range only takes into account two values from the entire dataset, it may be heavily influenced by outliers in the data.
modeString
String
The most frequently occurring value in the dataset. Easy to determine, but subject to variation and of limited value.
sorted
Number
The data array sorted by numeric ascending, with none numeric values removed.
standardDeviation
Number
The standard deviation for a population using the deviation score method. Standard Deviation is the average deviation of the scores from the mean.
sum
Number
The sum.
unique
Number
An array in which any duplicated values in the data array are removed.
upperQuartile
Number
The upper quartile.
variance
Number
The variance for a population using the deviation score method. Variance is the average squared deviation of the scores from the mean.