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EPIB 698C Lecture 5

EPIB 698C Lecture 5. Raul Cruz-Cano. Creating and Redefining Variables. You can create and redefine variables with assignment statements as follows: Variable =expression. Vector Notation. Home gardener's data.

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EPIB 698C Lecture 5

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  1. EPIB 698C Lecture 5 Raul Cruz-Cano

  2. Creating and Redefining Variables • You can create and redefine variables with assignment statements as follows: Variable =expression Vector Notation

  3. Home gardener's data • Gardeners were asked to estimate the pounds they harvested for four corps: tomatoes, zucchini, peas and grapes. Here is the data: Gregor 10 2 40 0 Molly 15 5 10 1000 Luther 50 10 15 50 Susan 20 0 . 20 • Task: • add new variable group with a value of 14; • add variable type to indicate home gardener; • Create a new variable zucchini_1 which equals to zucchini*10 • derive total pounds of corps for each gardener; • derive % of tomatoes for each gardener

  4. Home gardener's data DATA homegarden; INFILE‘C:\garden.txt'; INPUT Name $ 1-7 Tomato Zucchini Peas grapes; group = 14; Type = 'home'; Zucchini_1= Zucchini * 10; Total=tomato + zucchini_1 + peas + grapes; PerTom = (Tomato / Total) * 100; Run; CODE

  5. Home gardener's data • Check the log window: Missing values were generated as a result of performing an operation on missing values. • Since for the last subject, we have missing values for peas, so we the variable total and PerTom, which are calculated from peas, are set to missing

  6. SAS functions • SAS has over 400 functions, with the following general form: Function-name (argument, argument, …) • All functions must have parentheses even if they don’t require any arguments • Example: • X=Int(log(10)); • Mean_score = mean(score1, score2, score3); The Mean function returns mean of non-missing arguments, which differs from simply adding and dividing by their number, which would return a missing values if any arguments are missing

  7. Common Functions And Operators • Functions ABS: absolute value EXP: exponential LOG: natural logarithm MAX and MIN: maximum and minimum SQRT: square root SUM: sum of variables Example:SUM (of x1-x10, x21) • Arithmetic: +, -, *, /, ** (not ^)

  8. More SAS functions CODE

  9. Selected date functions

  10. Working with SAS Date • A SAS date is a numeric value equal to the number of days since Jan. 1, 1960. For example: CODE

  11. Example: pumpkin carving contest data • This data contains contestant’s name , age, type of pumpkin (carved or decorated), date of entry and the scores from 5 judges. Alicia Grossman 13 c 10-28-2003 7.8 6.5 7.2 8.0 7.9 Matthew Lee 9 D 10-30-2003 6.5 5.9 6.8 6.0 8.1 Elizabeth Garcia 10 C 10-29-2003 8.9 7.9 8.5 9.0 8.8 Lori Newcombe 6 D 10-30-2003 6.7 5.6 4.9 5.2 6.1 Jose Martinez 7 d 10-31-2003 8.9 9.510.0 9.7 9.0 Brian Williams 11 C 10-29-2003 7.8 8.4 8.5 7.9 8.0 • We will derive the means scores using the “Mean” function • Transform values of “type” to upper case • Get the day of the month from the SAS date

  12. Example: pumpkin carving contest data DATA contest; INFILE‘C:\pumpkin.txt'; INPUT Name $16. Age Type $ @23 Date MMDDYY10. (Scr1 Scr2 Scr3 Scr4 Scr5) (4.1); AvgScore= MEAN(Scr1,Scr2,Scr3,Scr4, Scr5); DayEntered = DAY(Date); Type = UPCASE(Type); run; CODE

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