SAS认证考试(官方练习题集和校正答案)
1. A raw data file is listed
below.
The following program is
submitted using this file as
input:
data work.family;
infile 'file-
specification';
statement here> run; Which INPUT statement correctly reads the values for the variable Birthdate as SAS date values? a.input relation $ first_name $ birthdate date9.; b.input relation $ first_name $ birthdate mmddyy8.; c.input relation $ first_name $ birthdate : date9.; d.input relation $ first_name $ birthdate : mmddyy8.; Correct answer: d An informat is used to translate the calendar date to a SAS date value. The date values are in the form of two-digit values for month-day-year, so the MMDDYY8. informat must be used. When using an informat with list input, the colon-format modifier is required to correctly associate the informat with the variable name. You can learn about ?informats in Reading Date and Time Values ?the colon-format modifier in Reading Free-Format Data. 2. A raw data file is listed below. The following SAS program is submitted using the raw data file above as input: data employeestats; input name $ age weight; run; The following output is desired: Which of the following INFILE statements completes the program and accesses the data correctly? a.infile 'file-specification' pad; b.infile 'file-specification' dsd; c.infile 'file-specification' dlm=','; d.infile 'file-specification' missover; Correct answer: b The PAD option specifies that SAS pad variable length records with blanks. The MISSOVER option prevents SAS from reading past the end of the line when reading free formatted data. The DLM= option specifies the comma as the delimiter; however, consecutive delimiters are treated as one by default. The DSD option correctly reads the data with commas as delimiters and two consecutive commas indicating a missing value like those in this raw data file. You can learn about ?the PAD option in Reading Raw Data in Fixed Fields ?the MISSOVER option in Creating Multiple Observations from a Single Record ?the DLM= option and the DSD option in Reading Free-Format Data. 3. The following program is submitted: data numrecords; infile cards dlm=','; input agent1 $ agent2 $ agent3 $; cards; jones,,brownjones,spencer,brown ; run; What is the value for the variable named Agent2 in the second observation? a.Brown b.Spencer c.' ' (missing character value) d.There is no value because only one observation is created. Correct answer: d The CARDS statement enables you to read instream data. Any number of consecutive commas are considered to be a single delimiter as a result of the DLM= option, and the length of each variable defaults to 8 bytes. Therefore, the values jones, brownjon, and spencer are assigned to Agent1, Agent2, and Agent3, respectively, for the first observation. The rest of the data on the record is not read by the INPUT statement and is not output to the data set. You can learn about ?the CARDS statement in Creating SAS Data Sets from Raw Data ?the default length of variables in Reading Free- Format Data. 4. A raw data file is listed below. The following program is submitted using this file as input: data work.houses; infile 'file-specification'; run; Which one of the following INPUT statements reads the raw data file correctly? a.input @1 style $8. +1 sqfeet 4. +1 bedrooms 1. @20 baths 3. street 16. @40 price dollar8; b.input @1 style $8 +1 sqfeet 4. +1 bedrooms 1. @20 baths 3. street $16 @40 price dollar8.; c.input @1 style $8. +1 sqfeet 4. +1 bedrooms 1. @20 baths 3. street $16. @40 price dollar8.; d.input @1 style $8. +1 sqfeet 4. +1 bedrooms 1. @20 baths 3 street 16. @40 price dollar8.; Correct answer: c Formatted input requires periods as part of the informat name. The period is missing from the variables Style and Street in Answer b, the variable Baths in Answer d, and the variable Price in Answer a (which is also missing a dollar sign to read the variable Street as a character value). You can learn about formatted input and informats in Reading Raw Data in Fixed Fields. 5. The following SAS program is submitted at the start of a new SAS session: libname sasdata 'SAS-data-library'; data sasdata.sales; set sasdata.salesdata; profit=expenses-revenues; run; proc print data=sales; run; The SAS data set Sasdata.Salesdata has ten observations. Which one of the following explains why a report fails to generate? a.The DATA step fails execution. b.The SAS data set Sales does not exist. c.The SAS data set Sales has no observations. d.The PRINT procedure contains a syntax error. Correct answer: b The DATA step creates a permanent SAS data set, Sasdata.Salesdata. The PRINT procedure is printing a temporary SAS data set, Sales, that is stored in the Work library. At the beginning of the SAS session, Work.Sales does not exist. You can learn about creating permanent data sets with the DATA step in Creating SAS Data Sets from Raw Data temporary data sets in Basic Concepts. 6. Which action assigns a reference named SALES to a permanent SAS data library? a.Issuing the command: libref SALES 'SAS-data-library' b.Issuing the command: libname SALES 'SAS-data-library' c.Submitting the statement: libref SALES 'SAS-data-library'; d.Submitting the statement: libname SALES 'SAS-data-library'; Correct answer: d The LIBNAME statement assigns a reference known as a libref to a permanent SAS data library. The LIBNAME command opens the LIBNAME window. You can learn about the LIBNAME statement in Referencing Files and Setting Options. 7. The following SAS program is submitted: data newstaff; set staff; run; Which one of the following WHERE statements completes the program and selects only observations with a Hire_date of February 23, 2000? a.where hire_date='23feb2000'd; b.where hire_date='23feb2000'; c.where hire_date='02/23/2000'd; d.where hire_date='02/23/2000'; Correct answer: a A SAS date constant must take the form of one- or two-digit day, three-digit month, and two- or four-digit year, enclosed in quotation marks and followed by a d ('ddmmmyy You can learn about SAS date constants in Creating SAS Data Sets from Raw Data. 8. Which one of the following SAS date formats displays the SAS date value for January 16, 2002 in the form of 16/01/2002? a.DATE10. b.DDMMYY10. c.WEEKDATE10. d.DDMMYYYY10. Correct answer: b The requested output is in day-month-year order and is 10 bytes long, so DDMMYY10. is the correct format. Although WEEKDATE10. is a valid SAS format, it does not display the SAS date value as shown in the question above. DDMMYYYY10. is not a valid SAS date format, and the DATE w. format cannot accept a length of 10. You can learn about ?the DDMMYY10. format in Creating List Reports ?the WEEKDATE10. format in Reading Date and Time Values. 9. Which one of the following displays the contents of an external file from within a SAS session? a.the LIST procedure b.the PRINT procedure c.the FSLIST procedure d.the VIEWTABLE window Correct answer: c The PRINT procedure and VIEWTABLE window display the values in SAS data sets. The FSLIST procedure displays the values in external files. There is no LIST procedure in SAS. You can learn about ?the PRINT procedure in Creating List Reports ?the VIEWTABLE window in Referencing Files and Setting Options. 10. The SAS data set Sashelp.Prdsale contains the variables Sashelp.Prdsale is sorted primarily by Region and within Region by Salary in descending order. The following program is submitted: data one; set sashelp.prdsale; retain temp; by region descending salary; if first.region then do; temp=salary; output; end; if last.region then do; range=salary-temp; output; end; run; For each region, what is the number of observation(s) written to the output data set? a.0 b.1 c. 2 d.4 Correct answer: c The expression first.region is true once for each region group. The expression last.region is true once for each region group. Therefore, each OUTPUT statement executes once for a total of 2 observations in the output data set. You can learn about the FIRST.variable expression and the OUTPUT statement in Reading SAS Data Sets. 11. The following SAS program is submitted: proc contents data=sasuser.houses; run; The exhibit below contains partial output produced by the CONTENTS procedure. Which of the following describes the Sasuser.Houses data set? a.The data set is sorted but not indexed. b.The data set is both sorted and indexed. c.The data set is not sorted but is indexe d. d.The data set is neither sorted nor indexed. Correct answer: d The exhibit above shows partial output from the CONTENTS procedure, In the top right-hand column of the output, you see that Indexes has a value of 0, which indicates that no indexes exist for this data set. Also, Sorted has a value of NO, which indicates that the data is not sorted. You can learn about the CONTENTS procedure in Referencing Files and Setting Options. 12. The following SAS program is submitted: proc sort data=work.test; by fname descending salary; run; Which one of the following represents how the observations are sorted? a.The data set Work.Test is stored in ascending order by both Fname and Salary values. b.The data set Work.Test is stored in descending order by both Fname and Salary values. c.The data set Work.Test is stored in descending order by Fname and ascending order by Salary values. d.The data set Work.Test is stored in ascending order by Fname and in descending order by Salary values. Correct answer: d The DESCENDING keyword is placed before the variable name it modifies in the BY statement, so the correct description is in descending order by Salary value within ascending Fname values. You can learn about the SORT procedure and the DESCENDING keyword in Creating List Reports. 13. The following SAS program is submitted: title='EDU'; if title='EDU' then Division='Education'; else if title='HR' then Division='Human Resources'; else Division='Unknown'; run; Which one of the following represents the value of the variable Division in the output data set? https://www.sodocs.net/doc/332842537.html,catio https://www.sodocs.net/doc/332842537.html,cation c.Human Re d.Human Resources Correct answer: b The length of the variable Division is set to 9 when the DATA step compiles. Since the value of the variable Title is EDU, the first IF condition is true; therefore, the value of the variable Division is Education. You can learn about ?the length of a variable in Understanding DATA Step Processing ?IF-THEN statements in Creating and Managing Variables. 14. Which one of the following SAS programs creates a variable a.data work.airports; AirportCode='ord'; if AirportCode='ORD' City='Chicago'; run; b.data work.airports; AirportCode='ORD'; if AirportCode='ORD' City='Chicago'; run; c.data work.airports; AirportCode='ORD'; if AirportCode='ORD' then City='Chicago'; run; d.data work.airports; AirportCode='ORD'; if AirportCode='ORD'; then City='Chicago'; run; Correct answer: c The correct syntax for an IF-THEN statement is: IF expression THEN statement; In this example, the variable City is assigned a value of Chicago only if the expression AirportCode='ORD' is true. You can learn about IF-THEN statements in Creating and Managing Variables. 15. The following SAS program is submitted: code='DAL523'; code='SANFRAN604'; code='HOUS731'; length code $ 20; run; Which one of the following is the length of the code variable? a.6 b.7 c.10 d.20 Correct answer: a The DATA step first goes through a compilation phase, then an execution phase. The length of a variable is set during the compilation phase and is based on the first time the variable is encountered. In this case, the variable code is set to the length of the text string DAL523 which is 6 characters long. The next assignment statements are ignored during compilation. The LENGTH statement is also ignored since the length has already been established, but a note will be written to the log. You can learn about ?the compilation phase of the DATA step in Understanding DATA Step Processing ?the LENGTH statement in Creating and Managing Variables. 16. Which of the following statements creates a numeric variable a.IDnumber=4198; b.IDnumber='4198'; c.length IDnumber=8; d.length IDnumber $ 8; Correct answer: a The first reference to the SAS variable in the DATA step sets the name, type, and length of the variable in the program data vector (PDV) and in the output SAS data set. The assignment statement IDnumber=4198; is the first reference and creates a numeric variable named IDnumber with a default storage length of 8 bytes. You can learn about ?creating variables in the DATA step in Understanding DATA Step Processing ?numeric variables in Basic Concepts. 17. The following program is submitted: input jobcode $ salary name $; cards; FLAT1 70000 Bob FLAT2 60000 Joe FLAT3 30000 Ann ; run; data desc; set fltaten; if salary>60000 then description='Over 60'; else description='Under 60'; run; What is value of the variable named description when the value for salary is 30000? a.Under 6 b.Under 60 c.Over 60 d.' ' (missing character value) Correct answer: a The variable description is being created by the IF- THEN/ELSE statement during compilation. The first occurrence of the variable description is on the IF statement, and since it is assigned the value Over 60, the length of the variable is 7. Therefore, for the salary value of 30000, description has the value of Under 6 (the 0 is truncated.) You can learn about ?the compilation phase of the DATA step in Understanding DATA Step Processing ?IF-THEN/ELSE statements in Creating and Managing Variables. 18. A raw data file is listed below. The following program is submitted: data all_sales; infile 'file-specification'; input receipts; run; Which statement(s) complete(s) the program and produce(s) a running total of the Receipts variable? a.total+receipts; b.total 0; sum total; c.total=total+receipts; d.total=sum(total,receipts); Correct answer: a The SUM function and the assignment statement do not retain values across iterations of the DATA step. The sum statement total+receipts; initializes total to 0, ignores missing values of receipt, retains the value of total from one iteration to the next, and adds the value of receipts to total. You can learn about the sum statement in Creating and Managing Variables. 19. A raw data file is listed below. The following SAS program is submitted and references the raw data file above: data money; infile 'file-specification'; input year quantity; total=total+quantity; run; What is the value of total when the data step finishes executing? a.0 b.1 c.11 d. . (missing numeric value) Correct answer: d The variable Total is assigned a missing value during the compilation phase of the DATA step. When the first record is read in, SAS processes: total=.+2; which results in a missing value. Therefore the variable Total remains missing for all observations. You can learn about ?the compilation phase of the DATA step in Understanding DATA Step Processing ?using missing values with arithmetic operators in Creating SAS Data Sets from Raw Data. 20. The following program is submitted: average=mean(6,4,.,2); run; What is the value of average? a.0 b.3 c.4 d. . (missing numeric value) Correct answer: c The MEAN function adds all of the non-missing values and divides by the number of non-missing values. In this case, 6 + 4 + 2 divided by 3 is 4. You can learn about the MEAN function in Transforming Data with SAS Functions. 21. The following SAS program is submitted: Phonenumber=3125551212; Code='('!!substr(Phonenumber,1,3)!!')'; run; Which one of the following is the value of the variable Code in the output data set? a.( 3) b.(312) c.3 d.312 Correct answer: a An automatic data conversion is performed whenever a numeric variable is used where SAS expects a character value. The numeric variable is written with the BEST12. format and the resulting character value is right-aligned when the conversion occurs. In this example, the value of Phonenumber is converted to character and right-aligned before the SUBSTR function is performed. Since there are only 10 digits in the value of Phonenumber, the right-aligned value begins with two blanks. Therefore the SUBSTR function picks up two blanks and a 3, and uses the BEST12. format to assign that value to Code. Then, the parentheses are concatenated before and after the two blanks and a 3. You can learn about automatic data conversion and the SUBSTR function in Transforming Data with SAS Functions. 22. The following SAS program is submitted: data work.inventory; products=7; do until (products gt 6); products+1; end; run; Which one of the following is the value of the variable products in the output data set? a.5 b.6 c.7 d.8 Correct answer: d A DO UNTIL loop always executes at least once because the condition is not evaluated until the bottom of the loop. In the SAS program above, the value of Products is incremented from 7 to 8 on the first iteration of the DO UNTIL loop, before the condition is checked. Therefore the value of Products is 8. You can learn about DO UNTIL loops in Generating Data with DO Loops. 23. The following program is submitted: data work.test; set work.staff (keep=salary1 salary2 salary3); run; Which ARRAY statement completes the program and creates new variables? a.array salary{3}; b.array new_salary{3}; c.array salary{3} salary1-salary3; d.array new_salary{3} salary1-salary3; Correct answer: b Although each of the ARRAY statements listed above is a valid statement, only Answer B creates new variables named new_salary1, new_salary2 and new_salary3. Answer C and Answer D both create an array that groups the existing data set variables salary1, salary2, and salary3. Since the array in Answer A is named salary, it also uses the existing data set variables. You can learn about creating new variables in an ARRAY statement in Processing Variables with Arrays. 24. Which of the following permanently associates a format with a a.the FORMAT procedure b.a FORMAT statement in a DATA step c.an INPUT function with format modifiers d.an INPUT statement with formatted style input Correct answer: b To permanently associate a format with a variable, you use the FORMAT statement in a DATA step. You can use the FORMAT procedure to create a user-defined format. You use the INPUT function to convert character data values to numeric values with an informat. You use the INPUT statement to read data into a data set with an informat. You can learn about ?permanently assigning a format to a variable in Creating and Managing Variables ?the FORMAT statement in Creating List Reports ?the FORMAT procedure in Creating and Applying User-Defined Formats ?the INPUT function in Transforming Data with SAS Functions ?the INPUT statement in Reading Raw Data in Fixed Fields. 25. The following report is generated: Which of the following steps created the report? a.proc freq data=sasuser.houses; tables style price /nocum; format price dollar10.; label style="Style of homes" price="Asking price"; run; b.proc print data=sasuser.houses; class style; var price; table style,n price*mean*f=dollar10.; label style="Style of homes" price="Asking price"; run; c.proc means data=sasuser.houses n mean; class style; var price; format price dollar10.; label style="Style of homes" price="Asking price"; run; d.proc report data=sasuser.houses nowd headline; column style n price; define style / group "Style of homes"; define price / mean format=dollar8. "Asking price"; run; Correct answer: d The FREQ procedure cannot create the average asking price.