Ask Phil SPSS adding ilikert scales to create a total score for regression

hi everyone fill here and today's
question comes from Isaac I have two
independent variables training and
compensation on one dependent variable
performance my sample size of 100
training have 29 questions consists on
five point scale compensation 20
questions performance 24 questions
please can you help right this is to do
with regression and this is the case
where your variables consists of sub
variables and so like with independent
variables and also the dependent
variable you will need to for each
variable combine them into one and the
standard way to do this is add them end
up the scales so say with training you
have 29 questions on the liquid scale
you would add them up to illustrate I've
got here train 1 and train to say we
want the this is just we want to turn
this into one independent variable so on
that just add them up we'll go to
variable view you can see that I've
coated them each of them on the liquor
scale one to five in adding them up
under notes when i do that it says one
of the operands for on a frenetic
operation is other than a numeric
variable or other expression hell Oh
rather oh so let's see how she got that
will go transform to create a new
variable transform compute variable and
then we go give it a name let's call it
t3 and we add them trained one let's
train too and okay ah so that's the
error message she was talking about so
how did that happen okay it happened
because under variable view we've
trained to you can see that the type
here is string I text that needs to be
changed to numeric now if we run it
again
we'll find now we've created a new
variable two three and it's done it so
one plus two is three and so on second
thing i'll just point out to you is I've
got missing value which I've coded as 99
so when we used when we added them
notice the dot there why that is a
missing value because that is missing
plus one well overall it's missing isn't
it what I wanted to point that out to
you is because some people instead of
using the + command and compute variable
use the sum command so let's try that
let's give it a new name let's 84 and
some command train one drink too okay
now what happens if you use the sum
command look what happens in the missing
so whether you use the plus sign or the
some sign they treat the missing in two
different ways from the some sign the ad
sign is better because if you use a some
sign if you see that one it's like
saying it's one plus nothing but it's
not nothing something we don't know
because it's missing thanks to Isaac for
today's question