How to automatically calculate the SUS Score for a given spreadsheet in LibreOffice Calc? -

i have several spreadsheets sus-score usability test.

they have form:

                                            | disagree | | | | agree | think, use system |        x          | | | |                | found system complex              |                   |x| | |                | (..)                                        |                   | | | |       x        | (...)                                       |        x          | | | |                | 

to calculate sus-score have 3 rules:

• odd item: pos - 1
• even item: 5 - pos
• add score, multiply 2.5

so first entry (odd item) have: pos - 1 = 1 - 1 = 0

second item (even): 5 - pos = 5 - 2 = 3

now have several of spreadsheets , want calculate sus-score automatically. i've changed x 1 , tried use if(f5=1,5-1). need if-condition every column: =if(f5=1;5-1;if(e5=1;4-1;if(d5=1;3-1;if(c5=1;2-1;if(b5=1;1-1))))), there easier way calculate score, based on position in table?

i use helper table , sum() cells of helper table , multiply 2.5. formula (modified needed, see notes below) can start helper table , copy-pasted fill out entire table:

=if(d2="x";if(mod(row();2)=1;5-d$1;d$1-1);"") 

• here d answer column
• depending on row (odd/even) answers start may need change =1 after mod function =0
• this assumes position number in row 1; if position numbers in different row change number after $ appropriately