SAS Programming Interview Questions & Answers

  1. Question 1. Describe 5 Ways To Do A “table Lookup” In Sas?

    Answer :

    • Match Merging,
    • Direct Access,
    • Format Tables,
    • Arrays,
    • PROC SQL.
  2. Question 2. What Are Some Good Sas Programming Practices For Processing Very Large Data Sets?

    Answer :

    Sampling method using OBS option or subsetting, commenting the Lines, Use Data Null.

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  4. Question 3. Under What Circumstances Would You Code A Select Construct Instead Of If Statements?

    Answer :

    I think Select statement is used when you are using one condition to compare with severalconditions like.
    Data exam;
    Set exam;
    select (pass);
    when Physics gt 60;
    when math gt 100;
    when English eq 50;
    otherwise fail;

  5. Question 4. What Is The One Statement To Set The Criteria Of Data That Can Be Coded In Any Step?

    Answer :

    Options statement.

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  7. Question 5. What Is The Effect Of The Options Statement Errors=1?

    Answer :

    The –ERROR- variable has a value of 1 if there is an error in the data for that observation and 0 if it is not.

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  9. Question 6. What Do The Sas Log Messages “numeric Values Have Been Converted To Character” Mean? What Are The Implications?

    Answer :

    It implies that automatic conversion took place to make character functions possible.

  10. Question 7. Why Is A Stop Statement Needed For The Point= Option On A Set Statement?

    Answer :

    Because POINT= reads only the specified observations, SAS cannot detect an end-of-file condition as it would if the file were being read sequentially.

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  12. Question 8. How Do You Control The Number Of Observations And/or Variables Read Or Written?

    Answer :

    FIRSTOBS and OBS option.

  13. Question 9. Approximately What Date Is Represented By The Sas Date Value Of 730?

    Answer :

    INPUT, DATA and RUN.

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  15. Question 10. Does Sas ‘translate’ (compile) Or Does It ‘interpret’?

    Answer :


  16. Question 11. What Does The Run Statement Do?

    Answer :

    When SAS editor looks at Run it starts compiling the data or proc step, if you have more than one data step or proc step or if you have a proc step. Following the data step then you can avoid the usage of the run statement.

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  18. Question 12. Why Is Sas Considered Self-documenting?

    Answer :

    SAS is considered self documenting because during the compilation time it creates and stores all the information about the data set like the time and date of the data set creation later No. of the variables later labels all that kind of info inside the dataset and you can look at that info using proc contents procedure.

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  20. Question 13. What Is The Different Between Functions And Procs That Calculate Thesame Simple Descriptive Statistics?

    Answer :

    Functions can used inside the data step and on the same data set but with proc’s you can create a new data sets to output the results.

  21. Question 14. What Is A Method For Assigning First.var And Last.var To The By Groupvariable On Unsorted Data?

    Answer :

    In unsorted data you can’t use First. or Last.

  22. Question 15. How Do You Debug And Test Your Sas Programs?

    Answer :

    First thing is look into Log for errors or warning or NOTE in some cases or use the debugger in SAS data step.

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  24. Question 16. What Areas Of Sas Are You Most Interested In?

    Answer :

    BASE, STAT, GRAPH, ETSBriefly.

  25. Question 17. What Versions Of Sas Have You Used (on Which Platforms)?

    Answer :

    SAS 9.1.3,9.0, 8.2 in Windows and UNIX, SAS 7 and 6.12.

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  27. Question 18. What Are Some Problems You Might Encounter In Processing Missing Values? In Data Steps? Arithmetic? Comparisons? Functions? Classifying Data?

    Answer :

    The result of any operation with missing value will result in missing value. Most SAS statistical procedures exclude observations with any missing variable values from an analysis.

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  29. Question 19. How Would You Create A Data Set With 1 Observation And 30 Variables From A Data Set With 30 Observations And 1 Variable?

    Answer :


  30. Question 20. What Is The Different Between Functions And Procs That Calculate The Same Simple Descriptive Statistics?

    Answer :

    Proc can be used with wider scope and the results can be sent to a different dataset. Functions usually affect the existing datasets.

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  32. Question 21. If You Were Told To Create Many Records From One Record, Show How You Would Do This Using Array And With Proc Transpose?

    Answer :

    Declare array for number of variables in the record and then used Do loop Proc Transpose with VAR statement.

  33. Question 22. What Are _numeric_ And _character_ And What Do They Do?

    Answer :

    Will either read or writes all numeric and character variables in dataset.

  34. Question 23. How Would You Create Multiple Observations From A Single Observation?

    Answer :

    Using double Trailing @@.

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  36. Question 24. For What Purpose Would You Use The Retain Statement?

    Answer :

    The retain statement is used to hold the values of variables across iterations of the data step. Normally, all variables in the data step are set to missing at the start of each iteration of the data step. What is the order of evaluation of the comparison operators: + – * / ** ()?A) (), **, *, /, +, -.

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  38. Question 25. How Could You Generate Test Data With No Input Data?

    Answer :

    Using Data Null and put statement.

  39. Question 26. What Can You Learn From The Sas Log When Debugging?

    Answer :

    It will display the execution of whole program and the logic. It will also display the error with line number so that you can and edit the program.

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  41. Question 27. What Is The Purpose Of _error_?

    Answer :

    It has only to values, which are 1 for error and 0 for no error.

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  43. Question 28. How Can You Put A “trace” In Your Program?

    Answer :

    By using ODS TRACE ON.

  44. Question 29. How Does Sas Handle Missing Values In: Assignment Statements, Functions, A Merge, An Update, Sort Order, Formats, Procs?

    Answer :

    Missing values will be assigned as missing in Assignment statement. Sort order treats missing as second smallest followed by underscore.

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  46. Question 30. How Do You Test For Missing Values?

    Answer :

    Using Subset functions like IF then Else, Where and Select.

  47. Question 31. How Are Numeric And Character Missing Values Represented Internally?

    Answer :

    Character as Blank or  and Numeric as.

  48. Question 32. Which Date Functions Advances A Date Time Or Date/time Value By A Given Interval?

    Answer :


  49. Question 33. In The Flow Of Data Step Processing, What Is The First Action In A Typical Data Step?

    Answer :

    When you submit a DATA step, SAS processes the DATA step and then creates a new SAS data set.( creation of input buffer and PDV)
    Compilation Phase
    Execution Phase.

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  51. Question 34. What Are Sas/access And Sas/connect?

    Answer :

    SAS/Access only process through the databases like Oracle, SQL-server, Ms-Access etc.
    SAS/Connect only use Server connection.

  52. Question 35. What Is The Purpose Of Using The N=ps Option?

    Answer :

    The N=PS option creates a buffer in memory which is large enough to store PAGESIZE (PS) lines and enables a page to be formatted randomly prior to it being printed.

  53. Question 36. What Are The Scrubbing Procedures In Sas?

    Answer :

    Proc Sort with nodupkey option, because it will eliminate the duplicate values.

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  55. Question 37. What Are The New Features Included In The New Version Of Sas I.e., Sas9.1.3?

    Answer :

    The main advantage of version 9 is faster execution of applications and centralized access of data and support.

    There are lots of changes has been made in the version 9 when we compared with the version 8. The following are the few:

    • SAS version 9 supports Formats longer than 8 bytes & is not possible with version 8.
    • Length for Numeric format allowed in version 9 is 32 where as 8 in version 8.
    • Length for Character names in version 9 is 31 where as in version 8 is 32.
    • Length for numeric informat in version 9 is 31, 8 in version 8.

    Length for character names is 30, 32 in version 8.3 new informats are available in version 9 to convert various date, time and datetime forms of data into a SAS date or SAS time.

    • ANYDTDTEW. – Converts to a SAS date value
    • ANYDTTMEW. – Converts to a SAS time value.
    • ANYDTDTMW. -Converts to a SAS datetime value.CALL SYMPUTX Macro statement is added in the version 9 which creates a macro variable at execution time in the data step by
    • Trimming trailing blanks
    • Automatically converting numeric value to character.

    New ODS option (COLUMN OPTION) is included to create a multiple columns in the output.

  56. Question 38. What Differrence Did You Find Among Version 6 8 And 9 Of Sas?

    Answer :

    The SAS 9 Architecture is fundamentally different from any prior version of SAS. In the SAS 9 architecture, SAS relies on a new component, the Metadata Server, to provide an information layer between the programs and the data they access. Metadata, such as security permissions for SAS libraries and where the various SAS servers are running, are maintained in a common repository.

  57. Question 39. What Has Been Your Most Common Programming Mistake?

    Answer :

    Missing semicolon and not checking log after submitting program, Not using debugging techniques and not using Fsview option vigorously.

  58. Question 40. Name Several Ways To Achieve Efficiency In Your Program?

    Answer :

    Efficiency and performance strategies can be classified into 5 different areas.
    •CPU time
    •Data Storage
    • Elapsed time
    • Input/Output
    • Memory CPU Time and Elapsed Time- Base line measurements.

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  60. Question 41. What Other Sas Products Have You Used And Consider Yourself Proficient In Using?

    Answer :

    Data _NULL_ statement, Proc Means, Proc Report, Proc tabulate, Proc freq and Proc print, Proc Univariate etc.

  61. Question 42. What Is The Significance Of The ‘of’ In X=sum (of A1-a4, A6, A9);

    Answer :

    If don’t use the OF function it might not be interpreted as we expect. For example the function above calculates the sum of a1 minus a4 plus a6 and a9 and not the whole sum of a1 to a4 & a6 and a9. It is true for mean option also.

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  63. Question 43. What Do The Put And Input Functions Do?

    Answer :

    INPUT function converts character data values to numeric values.
    EX: for INPUT: INPUT (source, informat).

    PUT function converts numeric values to character values.
    For PUT: PUT (source, format).

  64. Question 44. Which Date Function Advances A Date, Time Or Datetime Value By A Given Interval?

    Answer :

    INTNX: INTNX function advances a date, time, or datetime value by a given interval, and returns a date, time, or datetime value.
    Ex: INTNX(interval,start-from,number-of-increments,alignment)

    INTCK: INTCK(interval,start-of-period,end-of-period) is an interval functioncounts the number of intervals between two give SAS dates, Time and/or datetime.

    DATETIME () returns the current date and time of day.

    DATDIF (sdate,edate,basis): returns the number of days between two dates.

  65. Question 45. What Do The Mod And Int Function Do? What Do The Pad And Dim Functions Do?

    Answer :

    MOD: Modulo is a constant or numeric variable, the function returns the reminder after numeric value divided by modulo.

    INT: It returns the integer portion of a numeric value truncating the decimal portion.

    PAD: it pads each record with blanks so that all data lines have the same length. It is used in the INFILE statement. It is useful only when missing data occurs at the end of the record.

    CATX: concatenate character strings, removes leading and trailing blanks and inserts separators.

    SCAN: it returns a specified word from a character value. Scan function assigns a length of 200 to each target variable.

    SUBSTR: extracts a sub string and replaces character values.Extraction of a substring:
    Middleinitial=substr(middlename,1,1); Replacing character values: substr (phone,1,3)=’433’; If SUBSTR function is on the left side of a statement, the function replaces the contents of the character variable.

    TRIM: trims the trailing blanks from the character values.

    SCAN vs. SUBSTR: SCAN extracts words within a value that is marked by delimiters. SUBSTR extracts a portion of the value by stating the specific location. It is best used when we know the exact position of the sub string to extract from a character value.

  66. Question 46. How Might You Use Mod And Int On Numeric To Mimic Substr On Character Strings?

    Answer :

    The first argument to the MOD function is a numeric, the second is a non-zero numeric; the result is the remainder when the integer quotient of argument-1 is divided by argument-2. The INT function takes only one argument and returns the integer portion of an argument, truncating the decimal portion. Note that the argument can be an expression.

    DATA NEW ;
    A = 123456 ;
    X = INT( A/1000 ) ;
    Y = MOD( A, 1000 ) ;
    Z = MOD( INT( A/100 ), 100 ) ;
    PUT A= X= Y= Z= ;
    RUN ;


  67. Question 47. In Array Processing, What Does The Dim Function Do?

    Answer :

    DIM: It is used to return the number of elements in the array. When we use Dim function we would have to re –specify the stop value of an iterative DO statement if u change the dimension of the array.

  68. Question 48. How Would You Determine The Number Of Missing Or Nonmissing Values In Computations?

    Answer :

    To determine the number of missing values that are excluded in a computation, use the NMISS function.

    data _null_;
    m = . ;
    y = 4 ;
    z = 0 ;
    N = N(m , y, z);
    NMISS = NMISS (m , y, z);

    The above program results in N = 2 (Number of non missing values) and NMISS = 1 (number of missing values).

  69. Question 49. Do You Need To Know If There Are Any Missing Values?

    Answer :

    Just use: missing_values=MISSING(field1,field2,field3);
    This function simply returns 0 if there aren’t any or 1 if there are missing values.If you need to know how many missing values you have then use num_missing=NMISS(field1,field2,field3);
    You can also find the number of non-missing values with non_missing=N (field1,field2,field3);

  70. Question 50. What Is The Difference Between: X=a+b+c+d; And X=sum (of A, B, C ,d);?

    Answer :

    Is anyone wondering why you wouldn’t just use total=field1+field2+field3;

  71. Question 51. First, How Do You Want Missing Values Handled?

    Answer :

    The SUM function returns the sum of non-missing values. If you choose addition, you will get a missing value for the result if any of the fields are missing. Which one is appropriate depends upon your needs.However, there is an advantage to use the SUM function even if you want the results to be missing. If you have more than a couple fields, you can often use shortcuts in writing the field names If your fields are not numbered sequentially but are stored in the program data vector together then you can use: total=SUM(of fielda–zfield); Just make sure you remember the “of” and the double dashes or your code will run but you won’t get your intended results. Mean is another function where the function will calculate differently than the writing out the formula if you have missing values.There is a field containing a date. It needs to be displayed in the format “ddmonyy” if it’s before 1975, “dd mon ccyy” if it’s after 1985, and as ‘Disco Years’ if it’s between 1975 and 1985.

  72. Question 52. What Is The Difference Between Calculating The ‘mean’ Using The Mean Function And Proc Means?

    Answer :

    By default Proc Means calculate the summary statistics like N, Mean, Std deviation, Minimum and maximum, Where as Mean function compute only the mean values.

  73. Question 53. What Are Some Differences Between Proc Summary And Proc Means?

    Answer :

    Proc means by default give you the output in the output window and you can stop this by the option NOPRINT and can take the output in the separate file by the statement OUTPUTOUT= , But, proc summary doesn’t give the default output, we have to explicitly give the output statement and then print the data by giving PRINT option to see the result.

  74. Question 54. Which Data Set Is The Controlling Data Set In The Merge Statement?

    Answer :

    Dataset having the less number of observations control the data set in the merge statement.

  75. Question 55. How Do The In= Variables Improve The Capability Of A Merge?

    Answer :

    The IN=variablesWhat if you want to keep in the output data set of a merge only the matches (only those observations to which both input data sets contribute)? SAS will set up for you special temporary variables, called the “IN=” variables, so that you can do this and more. Here’s what you have to do: signal to SAS on the MERGE statement that you need the IN= variables for the input data set(s) use the IN= variables in the data step appropriately, So to keep only the matches in the match-merge above, ask for the IN= variables and use them:data three;merge one(in=x) two(in=y); /* x & y are your choices of names */by id; /* for the IN= variables for data */if x=1 and y=1; /* sets one and two respectively */run;

  76. Question 56. What Techniques And/or Procs Do You Use For Tables?

    Answer :

    Proc Freq, Proc univariate, Proc Tabulate & Proc Report.

  77. Question 57. Do You Prefer Proc Report Or Proc Tabulate? Why?

    Answer :

    I prefer to use Proc report until I have to create cross tabulation tables, because, It gives me so many options to modify the look up of my table, (ex: Width option, by this we can change the width of each column in the table) Where as Proc tabulate unable to produce some of the things in my table. Ex: tabulate doesn’t produce n (%) in the desirable format.

  78. Question 58. What Is The Difference Between Nodup And Nodupkey Options?

    Answer :

    NODUP compares all the variables in our dataset while NODUPKEY compares just the BY variables.

  79. Question 59. What Is The Main Difference Between Rename And Label?

    Answer :

    1. Label is global and rename is local i.e., label statement can be used either in proc or data step where as rename should be used only in data step. 2. If we rename a variable, old name will be lost but if we label a variable its short name (old name) exists along with its descriptive name.

  80. Question 60. What Is Enterprise Guide? What Is The Use Of It?

    Answer :

    It is an approach to import text files with SAS (It comes free with Base SAS version 9.0).

  81. Question 61. What Are Input Dataset And Output Dataset Options?

    Answer :

    Input data set options are obs, firstobs, where, in output data set options compress, reuse.Both input and output dataset options include keep, drop, rename, obs, first obs.

  82. Question 62. How Can You Create Zero Observation Dataset?

    Answer :

    Creating a data set by using the like clause.ex: proc sql;create table latha.emp like oracle.emp;quit;In this the like clause triggers the existing table structure to be copied to the new table. using this method result in the creation of an empty table.
    In the editor window we write%include ‘path of the sas file’;run;if it is with non-windowing environment no need to give run statement.

  83. Question 63. How Can You Import .csv File In To Sas?

    Answer :

    To create CSV file, we have to open notepad, then, declare the variables.

    proc import datafile='E:age.csv' 
    out=sarath dbms=csv replace;
  84. Question 64. What Is The Use Of Proc Sql?

    Answer :

    PROC SQL is a powerful tool in SAS, which combines the functionality of data and proc steps. PROC SQL can sort, summarize, subset, join (merge), and concatenate datasets, create new variables, and print the results or create a new dataset all in one step! PROC SQL uses fewer resources when compared to that of data and proc steps. To join files in PROC SQL it does not require to sort the data prior to merging, which is must, is data merge.

  85. Question 65. What Is Sas Graph?

    Answer :

    SAS/GRAPH software creates and delivers accurate, high-impact visuals that enable decision makers to gain a quick understanding of critical business issues.

  86. Question 66. Why Is A Stop Statement Needed For The Point=option On A Set Statement?

    Answer :

    When you use the POINT= option, you must include a STOP statement to stop DATA step processing, programming logic that checks for an invalid value of the POINT= variable, or Both. Because POINT= reads only those observations that are specified in the DO statement, SAS cannot read an end-of-file indicator as it would if the file were being read sequentially. Because reading an end-of-file indicator ends a DATA step automatically, failure to substitute another means of ending the DATA step when you use POINT= can cause the DATA step to go into a continuous loop.

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