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Calculate Discount Factor and Add Into Syntax

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Eric Black

Calculate Discount Factor and Add Into Syntax

I have to add a discount factor for a variable in certain cases which is
based on an average ratio. For example, if I had two variables M1 and M2, I
would take M2 *if M2 is available*. If not, I would take M1, but I would
discount it by factor D. D is the average of M2/M1.

I am not sure if I can parse this ratio in or whether I need to first
calculate the ratio and then more or less manually enter it into my syntax file.

Any advice is greatly appreciated.

Matt

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Bruce Weaver

Re: Calculate Discount Factor and Add Into Syntax

Administrator

Something like this?

COMPUTE M2overM1 = M2/M1.

* Use AGGREGATE to get D, the mean of M2overM1, writing it to the current data set.
* Generate syntax via the GUI, or look it up in the FM.

DO IF not missing(M2).
- COMPUTE NewVar = M2.
ELSE.
- COMPUTE NewVar = { some expression involving M1 and D -- I'm not exactly sure what you mean }.
END IF.

matti wrote

I have to add a discount factor for a variable in certain cases which is
based on an average ratio. For example, if I had two variables M1 and M2, I
would take M2 *if M2 is available*. If not, I would take M1, but I would
discount it by factor D. D is the average of M2/M1.

I am not sure if I can parse this ratio in or whether I need to first
calculate the ratio and then more or less manually enter it into my syntax file.

Any advice is greatly appreciated.

Matt

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Bruce Weaver
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"When all else fails, RTFM."

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Eric Black

Re: Calculate Discount Factor and Add Into Syntax

In reply to this post by Eric Black

Thanks Bruce.

My problem with the FM is that I don't know where TH to look for in the FM ;)

I need to do it multiple times, in a simple but long drawn version, it is:
compute discount2 = M1/M2.
compute discount3 = M1/M3.
compute discount4 = M1/M4.

if sysmis(M1) M1 = M2*discount2.
exe.
if sysmis(M1) M1 = M3*discount3.
exe.
if sysmis(M1) M1 = M4*discount4.
exe.

Aggregate is only slightly more elegant than a simple mean table and then
using Excel to add the discount constants. I wasn't sure if there is an
elegant way of taking the results for discount2-4 directly within the syntax
file (I believe Stata allows that and I was hoping SPSS does so too)

Matt

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Bruce Weaver

Re: Calculate Discount Factor and Add Into Syntax

Administrator

Matt, it would help greatly if you provided a small sample data set (via DATA LIST) that shows what the data looks like initially, and what you want it to look like afterwards. (It would help me, at least.) ;-)

matti wrote

Thanks Bruce.

My problem with the FM is that I don't know where TH to look for in the FM ;)

I need to do it multiple times, in a simple but long drawn version, it is:
compute discount2 = M1/M2.
compute discount3 = M1/M3.
compute discount4 = M1/M4.

if sysmis(M1) M1 = M2*discount2.
exe.
if sysmis(M1) M1 = M3*discount3.
exe.
if sysmis(M1) M1 = M4*discount4.
exe.

Aggregate is only slightly more elegant than a simple mean table and then
using Excel to add the discount constants. I wasn't sure if there is an
elegant way of taking the results for discount2-4 directly within the syntax
file (I believe Stata allows that and I was hoping SPSS does so too)

Matt

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Eric Black

Re: Calculate Discount Factor and Add Into Syntax

In reply to this post by Eric Black

Below is a simplified example

data list list (",")/ id M1 to M4 (5f5.0).
begin data
1,1,2,3,4
2,2,3,2,3
3,,2, 2, 2
4,,,3, 3
end data.

compute discount2 = M1/M2.
compute discount3 = M1/M3.
compute discount4 = M1/M4.

mean tables discount2 to discount4/cell mean.

*This is the part where I would want the values of .5833 etc. to be added
automatically and not via the mean tables command.

if sysmis(M1) M1 = M2*.5833.
exe.
if sysmis(M1) M1 = M3*.6667.
exe.
if sysmis(M1) M1 = M4*.4583.
exe.

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David Marso

Re: Calculate Discount Factor and Add Into Syntax

Administrator

In reply to this post by Eric Black

If M1 is missing the *ALL* of your 'discount' variables will be missing.
You need to provide a SPECIFIC example of initial state and desired state of the data.

matti wrote

Thanks Bruce.

My problem with the FM is that I don't know where TH to look for in the FM ;)

I need to do it multiple times, in a simple but long drawn version, it is:
compute discount2 = M1/M2.
compute discount3 = M1/M3.
compute discount4 = M1/M4.

if sysmis(M1) M1 = M2*discount2.
exe.
if sysmis(M1) M1 = M3*discount3.
exe.
if sysmis(M1) M1 = M4*discount4.
exe.

Aggregate is only slightly more elegant than a simple mean table and then
using Excel to add the discount constants. I wasn't sure if there is an
elegant way of taking the results for discount2-4 directly within the syntax
file (I believe Stata allows that and I was hoping SPSS does so too)

Matt

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David Marso

Re: Calculate Discount Factor and Add Into Syntax

Administrator

In reply to this post by Eric Black

"Aggregate is only slightly more elegant than a simple mean table "
I beg to differ!!! Please review the AGGREGATE command in the FM prior to making such statements!
Hint: MODE=ADDVARIABLES is your friend!
--

matti wrote

Thanks Bruce.

My problem with the FM is that I don't know where TH to look for in the FM ;)

I need to do it multiple times, in a simple but long drawn version, it is:
compute discount2 = M1/M2.
compute discount3 = M1/M3.
compute discount4 = M1/M4.

if sysmis(M1) M1 = M2*discount2.
exe.
if sysmis(M1) M1 = M3*discount3.
exe.
if sysmis(M1) M1 = M4*discount4.
exe.

Aggregate is only slightly more elegant than a simple mean table and then
using Excel to add the discount constants. I wasn't sure if there is an
elegant way of taking the results for discount2-4 directly within the syntax
file (I believe Stata allows that and I was hoping SPSS does so too)

Matt

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Art Kendall

Re: Calculate Discount Factor and Add Into Syntax

In reply to this post by Eric Black

open a new instance of SPSS.
copy and paste the syntax below into a new syntax window and print it.

This seems to be what you are asking for but does not quite make sense.
By the way if you have a set of computes with the same variable on the left as in your post each will over write the previous one so that you only need that last one.

Please repost your data example with more field(s) called something like want1.

Art Kendall
Social Research Consultants

data list list (",")/ id M1 to M4 (5f5.0).
begin data
1,1,2,3,4
2,2,3,2,3
3,,2, 2, 2
4,,,3, 3
end data.
compute nobreak=1.
aggregate outfile=* mode = addvariables /break = nobreak
/ discount2 to discount4 = mean(m2 to m4).
formats discount2 to discount4(f6.4).
do if sysmis(m1).
compute newm1 = m4* discount4.
ELSE.
compute newm1 = m1.
end if.
formats newm1 (f6.4).
list.

On 4/16/2012 2:55 PM, Matt Kretschmer wrote:

Thanks Bruce.

My problem with the FM is that I don't know where TH to look for in the FM ;)

I need to do it multiple times, in a simple but long drawn version, it is:
compute discount2 = M1/M2.
compute discount3 = M1/M3.
compute discount4 = M1/M4.

if sysmis(M1) M1 = M2*discount2.
exe.
if sysmis(M1) M1 = M3*discount3.
exe.
if sysmis(M1) M1 = M4*discount4.
exe.


Aggregate is only slightly more elegant than a simple mean table and then
using Excel to add the discount constants.  I wasn't sure if there is an
elegant way of taking the results for discount2-4 directly within the syntax
file (I believe Stata allows that and I was hoping SPSS does so too)

Matt

=====================
To manage your subscription to SPSSX-L, send a message to
[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
SIGNOFF SPSSX-L
For a list of commands to manage subscriptions, send the command
INFO REFCARD

===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD

Art Kendall
Social Research Consultants

Bruce Weaver

Re: Calculate Discount Factor and Add Into Syntax

Administrator

In reply to this post by Eric Black

After your DATA LIST command:

DO REPEAT d = d2 to d4 / m = m2 to m4.
- COMPUTE d = M1 / m .
END REPEAT.

AGGREGATE
/OUTFILE=* MODE=ADDVARIABLES
/BREAK=
/discount2 to discount4 = MEAN(d2 to d4) .

DO REPEAT d = discount2 to discount4 / m = m2 to m4.
- IF SYSMIS(M1) M1 = m*d.
END REPEAT.
formats m1 to m4 (f5.3).
LIST id to m4.

If the number of terms is quite large, you might want to use VECTOR and LOOP rather than DO-REPEAT so that you can exit the loop as soon as SYSMIS(M1) is no longer true. See LOOP-END LOOP in the FM.

HTH.

matti wrote

Below is a simplified example

data list list (",")/ id M1 to M4 (5f5.0).
begin data
1,1,2,3,4
2,2,3,2,3
3,,2, 2, 2
4,,,3, 3
end data.

compute discount2 = M1/M2.
compute discount3 = M1/M3.
compute discount4 = M1/M4.

mean tables discount2 to discount4/cell mean.

*This is the part where I would want the values of .5833 etc. to be added
automatically and not via the mean tables command.

if sysmis(M1) M1 = M2*.5833.
exe.
if sysmis(M1) M1 = M3*.6667.
exe.
if sysmis(M1) M1 = M4*.4583.
exe.

=====================
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[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
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For a list of commands to manage subscriptions, send the command
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