Exam 1

Question 1

Types of variables and their definitions

Answer 1

Continuous: variable value can be measured along a numerical continuum (height, weight)

Categorical: variable value form category, either unordered (0 for male and 1 for female) or ordered (0 for low, 1 for medium, and 2 for high).

Question 2

Define observation

Answer 2

A set of data values for the same subject (name, age, height, weight, gender of one subject).

Question 3

Define a SAS data set:

Answer 3

a collection of observations

Question 4

Define a SAS statement

Answer 4

a command instructing SAS to perform certain action

Question 5

Define a SAS program

Answer 5

a set of SAS statements designed to perform a specific task

Question 6

List and define the four windows in SAS

Answer 6

Program (editor) window: This is where the program is written, edited and submitted.

Log window: It records the submitted program, including warnings and error message.

Output window: LISTING output from the submitted program. This is the default in SAS 9.2 and earlier versions.

Results Viewer: HTML output from the submitted program. This is the default in SAS 9.3.

Question 7

How to type in data?

Answer 7

DATA temp;
       Input \_\_\_\_ \_\_\_\_ \_\_\_\_ ect ;
datalines; (or cards;)
.
.
.
.

;
run;

Question 8

How to indicate that a variable is a character in SAS

Answer 8

in the input line type the name of the variable $

Question 9

How to print the results

Answer 9

proc print data=___ (obs=___); run;

note: only type the (obs=___) part if you are trying to print the first ___ observations

Question 10

List the naming conventions

Answer 10

SAS program: use extension ‘.sas’

SAS log: use extension ‘.log’

SAS output: use extension ‘.out’

Results Viewer: use extension ‘.mht’

Question 11

What are the 7 descriptive statistic commands (from section 1) in SAS?

Answer 11

proc contents

proc means

proc univariate

proc freq

proc corr

proc plot

proc gchart

Question 12

How is the descriptive statistic command “proc contents” command written and what does it do?

Answer 12

proc contents data=___ ; run;
(Tells us the number of observations, Variables, Indexes, Observation length, Deleted observations, and if its compressed or sorted. Also use this to find out how the data is coded. Is it numerical or something else? The variable name and the #s must be the same code.)

Question 13

How is the descriptive statistic command “proc means” command written and what does it do?

Answer 13

proc means data=___; run;

Gives us the means, Std Dev, Minimum, and Maximum for the variables

Question 14

How is the descriptive statistic command “proc univariate” command written and what does it do?

Answer 14

proc univariate data=___;
var ___;
run;
(the var ___ specifies which variable you are interested in. The command gives us the statistics for that specific variable.)

Question 15

How is the descriptive statistic command “proc freq” command written and what does it do?

Answer 15

proc freq data=___;
tables ____;
run;
(gives a frequency table of the selected variable. The columns in the table include: variable observation number, frequency, percent, cumulative frequency, and cumulative percent).

Question 16

How is the descriptive statistic command “proc corr” command written and what does it do?

Answer 16

proc corr data=___;
var ___ ___ ___ ect ;
run;
(this program allows you to test for any correlation between the selected variables. Gives the N, mean, std dev, sum, min, and max for each of the variables. Also reports the pearson correlation coefficients between all the selected variables).

Question 17

How is the descriptive statistic command “proc plot” command written and what does it do?

Answer 17

proc plot data=\_\_\_;
  plot variable Y * variable X='*';
  plot variable Y * variable X=\_\_\_;
  title "\_\_\_\_\_\_\_\_";
run;

It gives us an X by Y scatter plot.

Question 18

How is the descriptive statistic command “proc gchart” command written and what does it do?

Answer 18

proc gchart data=auto ;
vbar price / levels= ___ (some number);
title “bar chart for price”;
run;

or

proc gchart data=auto;
pie make / sumvar= repair type=mean;
title “pie chart for make of mean of repair by make”
run;

It gives us charts of the variables selected.

Question 19

Describe what the proc reg command looks like and what it does

Answer 19

proc reg data=____
___ ___ = ____ ____ ____ …;
title “ regression analysis of ……”;
run;

the output gives us a regression output for the variables selected.

Question 20

Define and explain internal data sources

Answer 20

Internal Data Sources: Read data from within a SAS program using “datalines” or “cards” statement. The general format is:

data data_set_name;
    infile dataline options;
    input variable_name_list;
 datalines;
.
.
.
.

;
run;

Question 21

How to read data from internal data sources as free formatted data (space delimited)

Answer 21

Notes: the infile statement is dropped in this example because space is the default delimiter

DATA cars1;
   INPUT make $ model $ mpg weight price;
DATALINES;
GMC Concord 22 2930 4099
GMC Pacer 17 3350 4749
GMC Spirit 22 2640 3799
Buick Century 20 3250 4816
Buick Electra 15 4080 7827
;
RUN;

Question 22

How to read data from internal data sources as free formatted data (comma delimited)

Answer 22

DATA cars2;
   INFILE datalines delimiter=',';
   INPUT make $ model $ mpg weight price;
DATALINES;
GMC, Concord, 22, 2930, 4099
GMC, Pacer, 17, 3350, 4749
GMC, Spirit, 22, 2640, 3799
Buick, Century, 20, 3250, 4816
Buick, Electra, 15, 4080, 7827
;
RUN;

Question 23

How to read data from internal data sources as free formatted data (tab delimited)

Answer 23

DATA cars3;
INPUT make $ model $ mpg weight price;
DATALINES;
GMC Concord 22 2930 4099
GMC Pacer 17 3350 4749
GMC Spirit 22 2640 3799
Buick Century 20 3250 4816
Buick Electra 15 4080 7827
;
RUN;

Question 24

How to read data from internal data sources as fixed formated data

Answer 24

Usually, because there are no delimiters (such as spaces, commas, or tabs) to separate fixed formatted data (hence no need for infile statement in the following example), column definitions are required for every variable. This also requires the data to be in the same columns for each subject.

DATA cars4;
   INPUT makes $ 1-5 model $ 6-12 mpg 13-14 weight 15-18 price 19-22;
CARDS;
GMC  Concord2229304099
GMC  Pacer  1733504749
GMC  Spirit 2226403799
BuickCentury2032504816
BuickElectra1540807827
;
RUN;

Question 25

Define and explain external data sources:

Answer 25

Read data from an external file using INFILE statment

Question 26

How to read in data from external data sources as free formatted data (space delimited)

Answer 26

DATA list1;
INFILE ‘F:\ECON804\lab2datafiles\List.prn’ delimiter=” “;
INPUT name $ gender $ age;
RUN;

Notes: It is not necessary to include option delimiter=” “ in the INFILE statement because space is the default delimiter. Be careful using the space delimited data when a character variable has one or more single embedded blanks.

Question 27

How to read in data from external data sources as free formatted data (comma delimited)

Answer 27

DATA list2;
INFILE ‘F:\ECON804\lab2datafiles\List.csv’ delimiter=” “;
INPUT name $ gender $ age;
RUN;

Notes: When reading comma delimited data into SAS, make sure the numerical variables do not use the 1000 separator (,).

Question 28

How to read in data from external data sources as fixed formatted data

Answer 28

DATA list3;
INFILE ‘F:\ECON804\lab2datafiles\List.txt’ delimiter=” “;
INPUT name $ 1-6 gender $ 7 age 8-9;
RUN;