Chi-Sq test result difference when done Manually and by SAS - sas

I am trying to perform a chi-square test on my data using SAS University Edition.
Here is the strucure of my data
+----------+------------+------------------+-------------------+
| study_id | Control_id | study_mortality | control_mortality |
+----------+------------+------------------|-------------------+
| 1 | 50 | Alive | Alive |
| 1 | 52 | Alive | Alive |
| 2 | 65 | Dead | Dead |
| 2 | 70 | Dead | Alive |
+----------+------------+------------------+-------------------+
I am getting different results when I do the test with SAS Vs when I do it manually using an online calculator. I used the values from 'PROC FREQ' to calculate the Chi-Sq using online calculator. Here are the outputs of frequencies and the Chi-sq test. Can someone point where the issue is.
proc freq data = mydata;
tables study_mortality control_mortality;
where type=1;
run;
+-----------------+-------------------+
| study_mortality | Frequency |
+-----------------+-------------------
| Alive | 7614 |
| Dead | 324 |
+-----------------+-------------------+
+----------------- +-------------------+
| control_mortality| Frequency |
+----------------- +-------------------
| Alive | 6922 |
| Dead | 159 |
+----------------- +-------------------+
proc freq data = mydata;
tables study_mortality*control_mortality/ CHISQ;
where type=1;
run;
+-----------------+-------------------+---------+-------+
| | Control_mortality | | |
+-----------------+-------------------+---------+-------+
| Study_mortality | Alive | Dead | Total |
| Alive | 5515 | 134 | 5649 |
| Dead | 249 | 5 | 254 |
| Total | 5764 | 139 | 5903 |
+-----------------+-------------------+---------+-------+
Statistic DF Value Prob
Chi-Square 1 0.1722 0.6782
Likelihood Ratio Chi-Square 1 0.1818 0.6699
Continuity Adj. Chi-Square 1 0.0414 0.8388
Mantel-Haenszel Chi-Square 1 0.1722 0.6782
Phi Coefficient -0.0054
Contingency Coefficient 0.0054
Cramer's V -0.0054

You have missing data. Look at the N's on those tables.
Study Mortality is around 8000 and Control Mortality is around 7000 but when you cross them you only have 5903 records. This means that certain records are excluded. There should be a line in the output saying N missing somewhere. Not sure if SAS didn't put it there or you only pasted selected output. The P value matches exactly when I use an online calculator and also match your output.
data have;
infile cards;
input Study Control N;
cards;
1 1 5515
1 0 134
0 1 249
0 0 5
;
run;
proc freq data=have;
table study*control / chisq;
weight N;
run;

Related

Grouping child items and displaying parent sum

I have the following table
+-------+--------+---------+
| group | item | value |
+-------+--------+---------+
| 1 | a | 10 |
| 1 | b | 20 |
| 2 | b | 30 |
| 2 | c | 40 |
+-------+--------+---------+
I would like to group the table by group, insert the grouped sum into value, and then ungroup:
+-------+--------+
| item | value |
+-------+--------+
| 1 | 30 |
| a | 10 |
| b | 20 |
| 2 | 70 |
| b | 30 |
| c | 40 |
+-------+--------+
The purpose of the result is to interpret the first column as items a and b belonging to group 1 with sum 30 and items b and c belonging to group 2 with sum 70.
Such a data transformation can be indicative of a reporting requirement more than a useful data structure for downstream processing. Proc REPORT can create output in the form desired.
data have;
infile datalines;
input group $ item $ value ##; datalines;
1 a 10 1 b 20 2 b 30 2 c 40
;
proc report data=have;
column group item value;
define group / order order=data noprint;
break before group / summarize;
compute item;
if missing(item) then item=group;
endcomp;
run;
I assume that both group and item are character variables
data have;
infile datalines firstobs=4 dlm='|';
input group $ item $ value;
datalines;
+-------+--------+---------+
| group | item | value |
+-------+--------+---------+
| 1 | a | 10 |
| 1 | b | 20 |
| 2 | b | 30 |
| 2 | c | 40 |
+-------+--------+---------+
;
data want (keep=group value);
do _N_=1 by 1 until (last.group);
set have;
by group;
v + value;
end;
value = v;output;v=0;
do _N_=1 to _N_;
set have;
group = item;
output;
end;
run;

Proc sql and macro variables

I am trying to run a code that should work on tables created considering different factors. As these factors can be more than 1, I decided to create a macro %let to list them:
%let list= factor1 factor2 ...;
What I would like to do is run a code to create these tables using different factors. For each factor, I computed using proc means the mean and the standard deviation, so I should have the variables &list._mean and &list._stddev in the table created by the proc means for each factor. This table is labelled as t2 and I need to join to another table, t1. From t1 I am considering all the variables.
My main difficulties are, therefore, in the proc sql:
proc sql;
create table new_table as
select t1.*
, t2.&list._mean as mean
, t2.&list._stddev as stddev
from table1 as t1
left join table2 as t2
on t1.time=t2.time
order by t2.&list.
quit;
This code is returning an error and I think because I am considering t2.factor1 factor2, i.e. t2 is only applied to the first factor, not to the second one.
What I would expect is the following:
proc sql;
create table new_table as
select t1.*
, t2.factor1._mean as mean
, t2.factor1._stddev as stddev
from table1 as t1
left join table2 as t2
on t1.time=t2.time
order by t2.factor1.
quit;
and another one for factor2.
UPDATE CODE:
%macro test_v1(
_dtb
,_input
,_output
,_time
,_factor
);
data &_input.;
set &_dtb..&_input.;
keep &_col_period. &_factor.;
run;
proc sort data = work.&_input.
out = &_input._1;
by &_factor. &_time.;
run;
%put ERROR: 2
proc means data=&_input._1 nonobs mean stddev;
class &_time.;
var &_factor.;
output out=&_input._n (drop=_TYPE_) mean= stddev= /autoname ;
run;
%put ERROR: 3
proc sql;
create table work.&_input._data as
select t1.*
,t2.&_factor._mean as mean
,t2.&_factor._stddev as stddev
from &_input. as t1
left join &_input._n as t2
on t1.&_time.=t2.&_time.
order by &_factor.;
quit;
%mend test_v1;
Then my question is on how I can consider multiple factors, defined into a macro as a list, as columns of tables and as input data into a macro (for example: %test(dataset, tablename, list).
I suspect that trying to use PROC SQL is what is making the problem hard. If you stick to just using normal SAS syntax your space delimited list of variable names is easy to use.
So taking your code and tweaking it a little:
%macro test_v1
(_dtb /* Input libref */
,_input /* Input member name */
,_output /* Output dataset */
,_time /* Class/By variable(s) */
,_factor /* Analysis variable(s) */
);
proc sort data= &_dtb..&_input. out=_temp1;
by &_time. ;
run;
proc means data=_temp1 nonobs mean stddev;
by &_time.;
var &_factor.;
output out=_temp2 (drop=_TYPE_) mean= stddev= /autoname ;
run;
data &_output. ;
merge _temp1 _temp2 ;
by &_time.;
run;
%mend test_v1;
We can then test it using SASHELP.CLASS by using SEX as the "time" variable and HEIGHT and WEIGHT as the analysis variables.
%test_v1(_dtb=sashelp,_input=class,_output=want,_time=sex,_factor=height weight);
You can try to add macro loop to your macros by scanning list of factors. It could look like:
%macro test(list);
%do i=1 to %sysfunc(countw(&list,%str( )));
%let factorname=%scan(&list,&i,%str( ));
/* if macro variable list equals factor1 factor2 then there would be
two iterations in loop, i=1 factorname=factor1 and i=2 factorname=2*/
/*your code here*/
%end
%mend test;
UPDATE:
%macro test(_input, _output, factors_list); %macro d; %mend d;
%do i=1 %to %sysfunc(countw(&factors_list,%str( )));
%let tfactor=%scan(&factors_list,&i,%str( ));
proc sort data = work.&_input.
out = &_input._1;
by &factors_list. time;
run;
proc means data=&_input._1 nonobs mean stddev;
class time;
var &tfactor.;
output out=&_input._num (drop=_TYPE_) mean= stddev= /autoname ;
run;
proc sql;
create table &_output._&tfactor as
select t1.*
, t2.&tfactor._mean as mean
, t2.&tfactor._stddev as stddev
from &_input as t1
left join &_input._num as t2
on t1.time=t2.time
order by t1.&tfactor;
quit;
%end;
%mend test;
%test(have,newdata,factor1 factor2);
Have dataset:
+------+---------+---------+
| time | factor1 | factor2 |
+------+---------+---------+
| 1 | 12345 | 1234 |
| 2 | 123 | 12 |
| 3 | 1 | -1 |
| 4 | -12 | -123 |
| 5 | -1234 | -12345 |
| 6 | 9876 | 987 |
| 7 | 98 | 8 |
| 8 | 9 | 7 |
| 1 | 1234 | 123 |
| 2 | 12 | 1 |
| 3 | 12 | -12 |
| 4 | -123 | -1234 |
| 5 | -12345 | -123456 |
| 6 | 987 | 98 |
| 7 | 9 | -9 |
| 8 | 1234 | 1234 |
+------+---------+---------+
NEWDATA_FACTOR1:
+------+---------+---------+---------+--------------+
| time | factor1 | factor2 | mean | stddev |
+------+---------+---------+---------+--------------+
| 5 | -12345 | -123456 | -6789.5 | 7856.6634458 |
| 5 | -1234 | -12345 | -6789.5 | 7856.6634458 |
| 4 | -123 | -1234 | -67.5 | 78.488852712 |
| 4 | -12 | -123 | -67.5 | 78.488852712 |
| 3 | 1 | -1 | 6.5 | 7.7781745931 |
| 7 | 9 | -9 | 53.5 | 62.932503526 |
| 8 | 9 | 7 | 621.5 | 866.20580695 |
| 3 | 12 | -12 | 6.5 | 7.7781745931 |
| 2 | 12 | 1 | 67.5 | 78.488852712 |
| 7 | 98 | 8 | 53.5 | 62.932503526 |
| 2 | 123 | 12 | 67.5 | 78.488852712 |
| 6 | 987 | 98 | 5431.5 | 6285.472178 |
| 1 | 1234 | 123 | 6789.5 | 7856.6634458 |
| 8 | 1234 | 1234 | 621.5 | 866.20580695 |
| 6 | 9876 | 987 | 5431.5 | 6285.472178 |
| 1 | 12345 | 1234 | 6789.5 | 7856.6634458 |
+------+---------+---------+---------+--------------+
NEWDATA_FACTOR2:
+------+---------+---------+----------+--------------+
| time | factor1 | factor2 | mean | stddev |
+------+---------+---------+----------+--------------+
| 5 | -12345 | -123456 | -67900.5 | 78567.341564 |
| 5 | -1234 | -12345 | -67900.5 | 78567.341564 |
| 4 | -123 | -1234 | -678.5 | 785.5956339 |
| 4 | -12 | -123 | -678.5 | 785.5956339 |
| 3 | 12 | -12 | -6.5 | 7.7781745931 |
| 7 | 9 | -9 | -0.5 | 12.02081528 |
| 3 | 1 | -1 | -6.5 | 7.7781745931 |
| 2 | 12 | 1 | 6.5 | 7.7781745931 |
| 8 | 9 | 7 | 620.5 | 867.62002052 |
| 7 | 98 | 8 | -0.5 | 12.02081528 |
| 2 | 123 | 12 | 6.5 | 7.7781745931 |
| 6 | 987 | 98 | 542.5 | 628.61792847 |
| 1 | 1234 | 123 | 678.5 | 785.5956339 |
| 6 | 9876 | 987 | 542.5 | 628.61792847 |
| 1 | 12345 | 1234 | 678.5 | 785.5956339 |
| 8 | 1234 | 1234 | 620.5 | 867.62002052 |
+------+---------+---------+----------+--------------+

SAS - Combine like values within rows, then add new variable for non like value(s)

I have a large dataset and am trying to run an analyses on each customer (same account and routing #), which have 100's of transactions within the dataset. I
was able to add SEQ # for like acct#'s and routing #s. How would I run an analyses to say SEQ #1 and give total # of deposits (Amount), max, min of deposits and potentially some other helpful data.
+-----------+--------+---------+--------+
| Routing# | Acct# | AMOUNT | TOTAL |SEQ #
+-----------+--------+---------+--------+
| 518 | 0 | 490.50 | 3777.5 | 1
| 518 | 0 | 170.00 | 3777.5 | 1
| 518 | 0 | 3117.00 | 3777.5 | 1
| 518 | 99 | 875.00 | 875 | 2
| 518 | 999 | 499.00 | 499 | 3
| 519 | 2 | 100.00 | 200.00 | 4
| 519 | 2 | 100.00 | 200.00 | 4
+-----------+--------+---------+--------+
Thanks
There are multiple ways to do this, but here is a data step way
data have;
input Routing Acct AMOUNT;
datalines;
518 0 490.50
518 0 170.00
518 0 3117.00
518 99 875.00
518 999 499.00
519 2 100.00
519 2 100.00
;
data want;
do until (last.Acct);
set have;
by Routing Acct notsorted;
total+amount;
end;
seq+1;
do until (last.Acct);
set have;
by Routing Acct notsorted;
output;
end;
total=0;
run;

Performing t-test using SAS when variables are in different columns

I have data which looks like following.
I was wondering how to run a t-test when variables that I want to compare are in different columns
+---------+------------+----------+-------------+-------------+----------------+
| Case_id | Control_id | case_age | control_age | case_result | control_result |
+---------+------------+----------+-------------+-------------+----------------+
| 1 | 50 | 24 | 24 | 23 | 12 |
| 1 | 52 | 24 | 24 | 23 | 10 |
| 2 | 65 | 27 | 27 | 24 | 15 |
| 2 | 70 | 27 | 27 | 24 | 14 |
+---------+------------+----------+-------------+-------------+----------------+
The SAS tutorials indicate the following syntax for running a t-test. But in my case I do not have a class variable to distinguish between cases and control. Is there a way to tell SAS to compare two variables case_result and control_result.
proc ttest data;
class Gender;
var Score;
run;
If you would like to compare two variables, it can be done this way:
proc compare base=libname.dataset allstats briefsummary;
var var1;
with var2;
title 'Comparison two variables';
run;
To run ttest on difference b/w two variables (paired comparison),
proc ttest data=libname.dataset;
paired var1*var2;
run;

Fill the blank values of a variable with the previous non blank value SAS 9.3

I'm using a dataset which is something like :
+----------+--------+-------+
| Variable | Level | Value |
+----------+--------+-------+
| sexe | men | 10 |
| | female | 20 |
| age | 0-20 | 5 |
| | 20-40 | 5 |
| | 40-60 | 10 |
| | >60 | 10 |
+----------+--------+-------+
And I would like to fulfill the "blank" cells using the previous non-blank cell to obtain something like this.
+----------+--------+-------+
| Variable | Level | Value |
+----------+--------+-------+
| sexe | men | 10 |
| sexe | female | 20 |
| age | 0-20 | 5 |
| age | 20-40 | 5 |
| age | 40-60 | 10 |
| age | >60 | 10 |
+----------+--------+-------+
I tried various possibilities in DATA step mostly with the LAG() function. The idea was to read the previous row when the cell was empty and fill with that.
DATA test;
SET test;
IF variable = . THEN DO;
variable = LAG1(variable);
END;
RUN;
And I obtained
+----------+--------+-------+
| Variable | Level | Value |
+----------+--------+-------+
| | men | 10 |
| sexe | female | 20 |
| | 0-20 | 5 |
| age | 20-40 | 5 |
| | 40-60 | 10 |
| | >60 | 10 |
+----------+--------+-------+
The problem was the good string is not always just one row upper. But I don't understand why SAS put blank in the first and 3d line. It didn't have to modify this line because I said "If variable = .".
I know how to do this in Python or in R with some for loop but I didn't find good solution in SAS.
I tried to put the string inside a variable with "CALL SYMPUT" and also with "RETAIN" but it didn't work too.
There must be a simple and elegant way to do this. Any idea?
You can't use LAG inside an IF and get that result - LAG doesn't actually work the way you think. RETAIN is the correct way I'd say:
DATA test;
SET test;
retain _variable;
if not missing(variable) then _variable=variable;
else variable=_variable;
drop _variable;
RUN;
Lag doesn't actually go to the previous record and get its value; what it does is set up a queue, and each time LAG is called it takes off a record from the front and adds a record to the back. This means that if LAG is inside a conditional block, it won't execute for the false condition, and you don't get your queue. You can use IFN and IFC functions, which evaluate both true and false conditions regardless of the boolean, but in this case RETAIN is probably easier.