Just one dimension

Sorry for the noob question, but how do I link just the z-pos of a layer to
slider effect? When I pick whip, I get the [temp, temp, temp]. I know I could
enter a manual value for the x and y, but the problem is that I'm going to have
about 70 other layers linking to that expression, and they all have different
x/y values. I'm guessing that I have to define variables first for x and y, but
I'm unsure on how to proceed.

I looked at Dan's site, and think this might be on the right track, but I can't
get the "value" to work with this, and I don't have set z-position
values (as opposed to the fixed amplitude and frequency values for the wiggle).

Just change the last line to

[value[0], value[1], temp]

Thanks Dan!
I tried:

[value, value, temp]

How might I go about adding a random offset to the start time of the individual
objects based on the slider movement?
Would I modify the expression using seedRandom(), or should I use a random()
with max/min values specified?

(current expression)

temp =
thisComp.layer("star_control").effect("StarZposControl")(&qu
ot;Slider");
[value[0], value[1], temp]

Should I define a variable called "delay" and then set up a random
value for delay?

Thanks,

Not sure if this is what you mean, but this will offset any keyframed slider
control values by between 0 and 2 seconds:

seedRandom(1, true);
delay = random(0,2);
temp =
thisComp.layer("star_control").effect("StarZposControl")(&qu
ot;Slider").valueAtTime(time - delay) ;