Advanced Functions

Overview

When you run a report Yellowfin performs calculations on the data returned from the database. With analytic functions you can further transform your data for analysis purposes by applying predefined calculations.

Functions are similar to aggregate functions. You simply select the field you wish the function to apply to, and choose the function you wish to use.

Available Functions

Yellowfin comes with a set of pre-defined functions. However, your administrator may add in additional functions specifically for your organisation or reporting needs. Expand the following to see the lists of functions available:

Statistical

Decile	Decile divides the rows returned into 10 equal parts, and assigns a value of 1 to 10, based upon its rank to the highest value. Deciles are used as a measure of dispersion.
Deviation	The number of deviations from the mean.
Linear Regression	A linear trendline is a best-fit straight line that is used with simple linear data sets. Your data is linear if the pattern in its data points resembles a line. A linear trendline usually shows that something is increasing or decreasing at a steady rate.
Mean	The arithmetic mean (or simply the mean) of a list of numbers is the sum of all the members of the list divided by the number of items in the list.
Median	The median is described as the number separating the higher half of a sample, a population, or a probability distribution, from the lower half.
Mode	The mode is the value that occurs the most frequently in a data set
Moving Average	A moving average trendline smoothes out fluctuations in data to show a pattern or trend more clearly. A moving average uses a specific number of data points (set by the Period option), averages them, and uses the average value as a point in the line. If Period is set to 2, for example, then the average of the first two data points is used as the first point in the moving average trendline. The average of the second and third data points is used as the second point in the trendline, and so on.
Moving Total	The total over the last N periods.
Naïve Forecasting	A naive forecasting model is a special case of the moving average forecasting model where the number of periods used for smoothing is 1. Therefore, the forecast for a period, t, is simply the observed value for the previous period, t-1. Due to the simplistic nature of the naive forecasting model, it can only be used to forecast up to one period in the future. It is not at all useful as a medium-long range forecasting tool.
Polynomial Regression	A polynomial trendline is a curved line that is used when data fluctuates. It is useful, for example, for analysing gains and losses over a large data set. The order of the polynomial can be determined by the number of fluctuations in the data or by how many bends (hills and valleys) appear in the curve. An Order 2 polynomial trendline generally has only one hill or valley. Order 3 generally has one or two hills or valleys. Order 4 generally has up to three.
Quartile	Quartile divides the rows returned into 4 equal parts, and assigns a value of 1 to 4, based upon its rank to the highest value. Quartiles are used as a measure of dispersion.
Standard Deviation	The standard deviation is a measure of the dispersion of a set of values. It can apply to a probability distribution, a random variable, a population or a multiset.
Standard Score	The standard score indicates how many standard deviations an observation is above or below the mean. It allows comparison of observations from different normal distributions, which is done frequently in research.
Variance	Returns the difference between the data sets.
Weighted Moving Average	Returns a moving average that is weighted so that the more recent the value, the more weight is applied to it.

Date

Days Between Date	The days between the date selected and another date column on the report.
Days to Now	The days between the date selected and the current date. (age in days)
Months Between Date	The months between the date selected and another date column on the report.
Months to Now	The months between the date selected and the current date. (age in months)
Weeks Days Between	The week days between the date selected and another date column on the report.
Years Between Date	The years between the date selected and another date column on the report.
Years to Now	The years between the date selected and the current date. (age in years)

Text

Concatenate

Joins two columns into one text string.

Analysis

Accumulative Percentage	Will print a running percentage for the values returned. A maximum of 100% will be displayed.
Accumulative Total	Will print out a running total for the data returned.
Ascending Rank	The highest value returned will be displayed as a 1. Used where the preferable result is a higher value. Eg. Profit.
Bottom 10 Rank	The bottom 10 values (lowest) are returned.
Bottom N Rank	The bottom N values (lowest) are returned- user is prompted to define number to return.
Delta from Last	Calculate change between consecutive rows
Delta from Last N	Calculate change between the current row and row - N
Descending Rank	The lowest value returned will be displayed as a 1. Used where the preferable result is a lower value. Eg. Expenses.
Difference of Columns	Returns difference of two selected columns
Multiplication of Columns	Returns multiplication of two selected columns
Natural Logarithm	Gives the base e logarithm of the values of a given field.
Natural Logarithm	Gives the base e logarithm of the values in the field.
Percentage Against Absolute Maximum	Returns percentage of selected field according to an absolute maximum value.
Percentage Against Column	Creates a percentage ration of values in the selected column compared to another column.
Percentage Against Maximum	Returns the % of the attribute when compared to the maximum value of the attribute within the dataset.
Percentage of Total	Returns the % of the attribute when compared to the total summed value of the attribute for the entire dataset.
Sum of Columns	Returns the sum of two selected columns.
Top 10 Rank	The top 10 values (highest) are returned.
Top N Rank	The top N values (highest) are returned - user is prompted to define number to return.
Top N With Ties	Returns top values for the selected field with provision for tied values. This means that if there are multiple records per ranking it will restrict it to N total rankings.

Applying a Function to an Item

1. To apply a function to an item, drag the field onto your report.
2. Highlight the item and click the function icon.
3. The function popup will open. This will display a range of functions available for the particular function type. For example if you have chosen a date variable then only date functions will be displayed.
4. Select the function type and then the specific function. By highlighting the functions available the description will appear at the bottom of the function list.
   
5. If appropriate select the aggregation. For example you can create a running total for SUM of revenue rather than revenue. This will pre-aggregate your data prior to the running total being applied.
6. Click OK to close and save your function.
   
7. When you run your report your column will now have the function formula applied.
   

Removing a Function

To remove a function from an item, do one of the following:

1. Reset the field by selecting the metric and clicking the clear button.
2. Remove the item from the report entirely
   

Statistical Functions

Yellowfin has a set of statistical functions which you can apply to your data. These include regressions and moving averages. These are applied as analytical functions and can result in trend lines such as the example below.