SPSS loops and IFs
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Hi All,
I have 2000 variables, each representing a single day (day_1 TO day_2000), each containing either a 0 or a 1.... child absent vs. child present, respectively.
The children are always present on day_1 and I would like to be able to calculate the number of days between day_1 and the last day they were present.
At first I thought...
COMPUTE Duration = 0.
IF(Day_2 = 1)Duration = 2.
IF(Day_3 = 1)Duration = 3.
and so on... out to day_2000
But at 2000 days... that is a lot of IF statements!
I have very little knowledge of loops and have been reading up on them... but I can't quite get my head wrapped around how to set this up.
Please someone save me from writing 2000 IF statements!!!
Cheers
Derek
-- Dr. Derek J. Quinlan Research Project Coordinator Psychology Lecturer University of Western Ontario London, Ontario Mailing Address: Dr. Derek J. Quinlan The University of Western Ontario Westminster Hall, Suite 326E London, ON N6A 3K7 |
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Wouldn't the following work:
Compute days_sum=sum(Day_1 to Day_2000).
Assuming the Day_1 to Day200 are contiguous variables.
Given
that your variables are coded 0 and 1, the sum would reflect
the
number of days the child was present. The following
should
also work:
Count days_#=Day_1 to Day_2000 (1).
Mike Palij
New York University
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In reply to this post by Derek Quinlan
You might want to look into the Count command, as in: count duration=day_1 to day_2000 (1).
Hi All, I have 2000 variables, each representing a single day (day_1 TO day_2000), each containing either a 0 or a 1.... child absent vs. child present, respectively. The children are always present on day_1 and I would like to be able to calculate the number of days between day_1 and the last day they were present. At first I thought... COMPUTE Duration = 0. IF(Day_2 = 1)Duration = 2. IF(Day_3 = 1)Duration = 3. and so on... out to day_2000 But at 2000 days... that is a lot of IF statements! I have very little knowledge of loops and have been reading up on them... but I can't quite get my head wrapped around how to set this up. Please someone save me from writing 2000 IF statements!!! Cheers Derek -- Dr. Derek J. Quinlan Research Project Coordinator Psychology Lecturer University of Western Ontario London, Ontario Mailing Address: Dr. Derek J. Quinlan The University of Western Ontario Westminster Hall, Suite 326E London, ON N6A 3K7 |
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Hi Rick,
I had done something very similar to that in order to calculate how many days the child actiually attended, but what I was hoping to do here was to calculate the numeber of days between the first and last visit (i.e. if the child was seen on day_1 and the last time they were seen was Day_1338, then the duration would be 1338 days).
Cheers
Derek
On Fri, Feb 12, 2010 at 3:06 PM, Rick Oliver <[hidden email]> wrote:
-- Dr. Derek J. Quinlan Research Project Coordinator Psychology Lecturer University of Western Ontario London, Ontario Mailing Address: Dr. Derek J. Quinlan The University of Western Ontario Westminster Hall, Suite 326E London, ON N6A 3K7 |
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In reply to this post by Derek Quinlan
You said, "I would like to be able to calculate the number of days between day_1 and the last day they were present", excluding day 1. If all of the variables are coded 1=present and 0=absent, why not just do this? compute dayspresent = sum(day_2 TO day_2000). exe.
--
Bruce Weaver bweaver@lakeheadu.ca http://sites.google.com/a/lakeheadu.ca/bweaver/ "When all else fails, RTFM." PLEASE NOTE THE FOLLOWING: 1. My Hotmail account is not monitored regularly. To send me an e-mail, please use the address shown above. 2. The SPSSX Discussion forum on Nabble is no longer linked to the SPSSX-L listserv administered by UGA (https://listserv.uga.edu/). |
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Hi Andres,
That is how I calculated the number of days the child was present... akin to what Rick had suggested.
However, I want to calculate the number of days total (whether seen or not) between day_1 and the last day they were present.
So the child could have attended day_1 and day_145 only, which I have already calculated as 2 days present, but what I am looking for is a way to calculate that there were 145 days between first and last day present.
Cheers
Derek
On Fri, Feb 12, 2010 at 3:17 PM, Bruce Weaver <[hidden email]> wrote:
-- Dr. Derek J. Quinlan Research Project Coordinator Psychology Lecturer University of Western Ontario London, Ontario Mailing Address: Dr. Derek J. Quinlan The University of Western Ontario Westminster Hall, Suite 326E London, ON N6A 3K7 |
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If I understand you, you want to know what is the last day that a
child was present. Working from Day_2000 backwards, consider the following subtitle 'Computing Last Day Student Attended'. compute last_day= 2000. vector Days_vec=Day_1 to Day_2000. loop #i=1 to 2000 if ((days_vec(2000-#i) eq 1)). compute last_day=(last_day - 1). end loop. var label last_day "Last Day Child Attended". desc var=last_day. -Mike Palij New York University [hidden email] ----- Original Message ----- From: Derek Quinlan To: [hidden email] Sent: Friday, February 12, 2010 3:24 PM Subject: Re: SPSS loops and IFs Hi Andres, That is how I calculated the number of days the child was present... akin to what Rick had suggested. However, I want to calculate the number of days total (whether seen or not) between day_1 and the last day they were present. So the child could have attended day_1 and day_145 only, which I have already calculated as 2 days present, but what I am looking for is a way to calculate that there were 145 days between first and last day present. Cheers Derek On Fri, Feb 12, 2010 at 3:17 PM, Bruce Weaver <[hidden email]> wrote: Derek Quinlan wrote: > > Hi All, > > I have 2000 variables, each representing a single day (day_1 TO day_2000), > each containing either a 0 or a 1.... child absent vs. child present, > respectively. > The children are always present on day_1 and I would like to be able to > calculate the number of days between day_1 and the last day they were > present. > > At first I thought... > > COMPUTE Duration = 0. > IF(Day_2 = 1)Duration = 2. > IF(Day_3 = 1)Duration = 3. > > and so on... out to day_2000 > > But at 2000 days... that is a lot of IF statements! > > I have very little knowledge of loops and have been reading up on them... > but I can't quite get my head wrapped around how to set this up. > > Please someone save me from writing 2000 IF statements!!! > > Cheers > Derek > > > > > > > -- > Dr. Derek J. Quinlan > Research Project Coordinator > Psychology Lecturer > University of Western Ontario > London, Ontario > > > Mailing Address: > Dr. Derek J. Quinlan > The University of Western Ontario > Westminster Hall, Suite 326E > London, ON > N6A 3K7 > > You said, "I would like to be able to calculate the number of days between day_1 and the last day they were present", excluding day 1. If all of the variables are coded 1=present and 0=absent, why not just do this? compute dayspresent = sum(day_2 TO day_2000). exe. ----- -- Bruce Weaver [hidden email] http://sites.google.com/a/lakeheadu.ca/bweaver/ "When all else fails, RTFM." NOTE: My Hotmail account is not monitored regularly. To send me an e-mail, please use the address shown above. -- View this message in context: http://old.nabble.com/SPSS-loops-and-IFs-tp27568533p27568814.html Sent from the SPSSX Discussion mailing list archive at Nabble.com. ===================== 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 -- Dr. Derek J. Quinlan Research Project Coordinator Psychology Lecturer University of Western Ontario London, Ontario Mailing Address: Dr. Derek J. Quinlan The University of Western Ontario Westminster Hall, Suite 326E London, ON N6A 3K7 ===================== 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 |
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In reply to this post by Derek Quinlan
I don't have the time to do a test run but see if something like this
does it. compute duration = 1. do repeat day = day_2 to day2000/index=2 to 2000. if day duration=index. end repeat. Art Kendall Social Research Consultant On 2/12/2010 2:51 PM, Derek Quinlan wrote: > Hi All, > I have 2000 variables, each representing a single day (day_1 TO > day_2000), each containing either a 0 or a 1.... child absent vs. > child present, respectively. > The children are always present on day_1 and I would like to be able > to calculate the number of days between day_1 and the last day they > were present. > At first I thought... > COMPUTE Duration = 0. > IF(Day_2 = 1)Duration = 2. > IF(Day_3 = 1)Duration = 3. > and so on... out to day_2000 > But at 2000 days... that is a lot of IF statements! > I have very little knowledge of loops and have been reading up on > them... but I can't quite get my head wrapped around how to set this up. > Please someone save me from writing 2000 IF statements!!! > Cheers > Derek > > > -- > Dr. Derek J. Quinlan > Research Project Coordinator > Psychology Lecturer > University of Western Ontario > London, Ontario > > > Mailing Address: > Dr. Derek J. Quinlan > The University of Western Ontario > Westminster Hall, Suite 326E > London, ON > N6A 3K7 > ===================== 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 |
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In reply to this post by Derek Quinlan
At 03:24 PM 2/12/2010, Derek Quinlan wrote:
I want to calculate the number of days total (whether seen or not) between day_1 and the last day they were present. So the child could have attended day_1 and day_145 only, which I have already calculated as 2 days present, but what I am looking for is a way to calculate that there were 145 days between first and last day present. Untested -- some errors likely: NUMERIC FirstDay LastDay (F5). VECTOR Day=day_1 TO day_2000. LOOP #Day=1 TO 2000. . DO IF Day(#Day) EQ 1. . COMPUTE FirstDay = MIN(#Day,FirstDay). . COMPUTE LastDay = Max(#Day,LastDay). . END IF. END LOOP. COMPUTE Interval=LastDay-FirstDay+1. (The "+1" is so both the first and last days are counted as part of the interval.) ===================== 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 |
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In reply to this post by Derek Quinlan
How about: (unchecked and untested) something
like?
do
repeat
x= 1 to
2000
/y = day_1
to Day_2000
if y = 1 days =
x.
end
repeat.
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In reply to this post by Derek Quinlan
Thanks to everyone that offered their suggestions/help with my original syntax problem (as seen in the original email post way below).
Here's what worked.
vector vec=day_1 to day_2000.
loop #i=2000 to 2 by -1. do if vec(#i)=1. compute duration=#i. break. end if. end loop. EXECUTE. NEW PROBLEM:
I'd like to figure out how many days the child attended during the 30 days previous to their last visit.
(e.g. Child was last seen on day_1800... then count number of attended days from 1800 back to 1770)
Can't figure out how to work the 30 day part into this.
Any help would be greatly appreciated.
Derek
On Fri, Feb 12, 2010 at 3:51 PM, Derek Quinlan <[hidden email]> wrote:
-- Dr. Derek J. Quinlan Research Project Coordinator Psychology Lecturer University of Western Ontario London, Ontario Mailing Address: Dr. Derek J. Quinlan The University of Western Ontario Westminster Hall, Suite 326E London, ON N6A 3K7 |
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In reply to this post by Derek Quinlan
Derek,
I must be not understanding something about both your original question and this one but as I understand your original question you might have data like this for a kid. Id d1 .... D20 12 10011111001001111100 You said: The children are always present on day_1 and I would like to be able to calculate the number of days between day_1 and the last day they were present. It seems to me that this would work for your original question. Count dayspresent=d2 to d20(1). If (dayspresent ne 0) dayspresent=dayspresent-1. Rationale. There's two cases to consider. 1) never present after day 1. the count command returns a value of 0 but you don't need to decrement that by the last day because there was none. 2) present one or more times after day 1. the count returns the number of days including the last day, which you don't want to count. Therefore, subtract 1 from the count to exclude the last day. The new question is different because you need to find that last day present and look backwards 30 days and count the number of days present in that 30 period beginning, I'm assuming, with the day previous to the day of the last visit. For this you have to use a loop structure because you have to find that last visit. So this would be my whole syntax package. Count dayspresent=d2 to d20(1). If (dayspresent ne 0) dayspresent=dayspresent-1. Compute past30days=0. Compute #last=0. vector day = day_1 to day_2000. loop #i = 2000 to 2 by -1. + if (day(#i) eq 1 and #last eq 0) #last=#i. + if ((#last-#i) ge 1) past30days=past30days+days(#i). end loop if ((#last-#i) eq 30). Gene Maguin Thanks to everyone that offered their suggestions/help with my original syntax problem (as seen in the original email post way below). Here's what worked. vector vec=day_1 to day_2000. loop #i=2000 to 2 by -1. do if vec(#i)=1. compute duration=#i. break. end if. end loop. EXECUTE. NEW PROBLEM: I'd like to figure out how many days the child attended during the 30 days previous to their last visit. (e.g. Child was last seen on day_1800... then count number of attended days from 1800 back to 1770) Can't figure out how to work the 30 day part into this. Any help would be greatly appreciated. Derek >>>On Fri, Feb 12, 2010 at 3:51 PM, Derek Quinlan <[hidden email]> wrote: I have 2000 variables, each representing a single day (day_1 TO day_2000), each containing either a 0 or a 1.... child absent vs. child present, respectively. The children are always present on day_1 and I would like to be able to calculate the number of days between day_1 and the last day they were present. At first I thought... COMPUTE Duration = 0. IF(Day_2 = 1)Duration = 2. IF(Day_3 = 1)Duration = 3. and so on... out to day_2000 But at 2000 days... that is a lot of IF statements! I have very little knowledge of loops and have been reading up on them... but I can't quite get my head wrapped around how to set this up. Please someone save me from writing 2000 IF statements!!! Cheers Derek ===================== 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 |
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In reply to this post by Derek Quinlan
Derek- Do you want to count their last visit in the 30 days? In
your example, counting 1800 back to 1770 is actually 31 days. So, do you
want to count 1770 to 1799 or 1771 to 1800? Also, what if the last day of
attendance was within the first 30 days? I’ll assume you’d
just take their total attendance. Since you said that day_1 is always 1, then your duration
variable is also equal to the last day of attendance. So, I think the
best solution is to use the same vector, but just not with a loop this time.
For example, “vec(duration)” would be the dichotomous day variable
of their last day of attendance and “vec(duration-1)” would be the
day before their last day and so on. I tried to use the TO keyword in the
sum but it gave me an error – perhaps one of the other list members can
help me understand why? [ compute last30=sum( vec(duration-30) TO
vec(duration) ). /* Gives an error. ] But since you only have 30 days,
it’s not awful to just have all 30 listed out. The tested syntax is below. If you want to count the last
day in the “last30”, then delete “vec(duration-30)”.
If you don’t want to count the last day, then delete “vec(duration)”.
As it is currently written, it’s actually counting 31 days.
Similarly, you may need to adjust the integer in the IF statement – “if
duration<=31” and “do if duration>31”. Did I
explain that well? Hope that helps, -Eric vector vec=day_1 to day_2000. * Find the duration of attendance. loop #i=2000 to 2 by -1. do if vec(#i)=1. compute duration=#i. break. end if. end loop. * Find the attendance for 30 days prior to last day. if duration<30 last30=sum(day_1 to day_30). do if duration>30. compute last30=sum( vec(duration), vec(duration-1), vec(duration-2), vec(duration-3), vec(duration-4), vec(duration-5), vec(duration-6), vec(duration-7), vec(duration-8), vec(duration-9), vec(duration-10), vec(duration-11), vec(duration-12), vec(duration-13), vec(duration-14), vec(duration-15), vec(duration-16), vec(duration-17), vec(duration-18), vec(duration-19), vec(duration-20), vec(duration-21), vec(duration-22), vec(duration-23), vec(duration-24), vec(duration-25), vec(duration-26), vec(duration-27), vec(duration-28), vec(duration-29), vec(duration-30)). end if. exe. From: Derek Quinlan
[mailto:[hidden email]] Thanks to everyone that offered their suggestions/help
with my original syntax problem (as seen in the original email post
way below). Here's what worked. vector vec=day_1 to day_2000. NEW PROBLEM: I'd like to figure out how many days the child attended
during the 30 days previous to their last visit. (e.g. Child was last seen on day_1800... then count number
of attended days from 1800 back to 1770) Can't figure out how to work the 30 day part into this. Any help would be greatly appreciated. Derek
On Fri, Feb 12, 2010 at 3:51 PM, Derek Quinlan <[hidden email]>
wrote: Hi All, I have 2000 variables, each representing a single
day (day_1 TO day_2000), each containing either a 0 or a 1.... child
absent vs. child present, respectively. The children are always present on day_1 and I would like to
be able to calculate the number of days between day_1 and the last day they
were present. At first I thought... COMPUTE Duration = 0. IF(Day_2 = 1)Duration = 2. IF(Day_3 = 1)Duration = 3. and so on... out to day_2000 But at 2000 days... that is a lot of IF statements! I have very little knowledge of loops and have been reading
up on them... but I can't quite get my head wrapped around how to set this up. Please someone save me from writing 2000 IF statements!!! Cheers Derek
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