To create these visualization I use the Sigmoid Function: S(t )=1/(1+e (-t ))
(more information here.)
In Tableau I use the function EXP(1) for e. So we need the create the input variable t. Therefore we need 4 fields.
Some Dimension (Name, Category, State, etc), Position 1 (ranking), Position 2 (ranking), t
To get the shape of the line I am going to plot 49 points for each Category (49 was simply used to get enough points to plot the shape of the curves and is the same number of values in t ). t = a value between -6 and 6 in .25 increments (which is 49 values)
The data file example is here so you can download and follow along in Tableau with these instructions (Source: Times Higher Education).
Step 1: Open Tableau and Import Data
Step 2: Create some calculated fields
Calculated Field Name: Sigmoid Function
Formula: 1/(1+EXP(1)^-[t])
Calculated Field Name: Color (optional)
Formula:
IF [Curve] <10.5 then 1
ELSEIF [Curve] <20.5 then 2
ELSEIF [Curve] <30.5 then 3
ELSEIF [Curve] <40.5 then 4
ELSE 5 END
Calculated Field Name: Size (optional)
Formula: ABS([Position 2]-[Position 1])
Step 3: Build the Viz
Move t to Columns
Move Curve to Rows
Move Name to Details
Set Marks to Line
Edit X-Axis to Fixed with Start = -10 and End = 10 (the extra space allows room for the labels - adjust as necessary)
Edit Y-Axis and Reverse Scale
Move Size to Size
Move Color to Color
Edit Color using Stepped Color with 5 Steps
Uncheck "Show Header" on Y-Axis and X-Axis
Move Name to Label
Select Left most points (at X = -6) and Select "Always Show" under Marks Label
Repeat for Right most points (at X = 6)
Format Curve to Number Format with 0 decimals
Move Curve to Label
Format Label to "<SUM(Curve)>. <Name>"
Format Sheet Lines to remove Gridlines and Zero Line (set to "None")
Format Sheet Borders to remove border (Row Divider and Column Divider Pane to "None")
Format Font Style/Color and Viz Spacing as needed
Click Color on the sheet and set "Markers" to "None". This will remove the dots at the end points.
