Quantitative data analysis

1. Quantitative data analysis Please review weeks 7 & 8 about quantitative research designs.

2. Make sure you look at the outline for writing section 3 • Most important is to get the research design right • Non-experimental • Pre-experimental • Quasi-experimental • True experimental

3. Then add specifics i.e. pre-experimental single group pre test post test quasi-experimental design using a natural control group with pre test and post test measures of both groups. quasi-experimental design using a single group time series design, with monthly measures of the outcomes

4. REVIEW • MOST OUTCOME EVALUATIONS INVOLVE COMPARISONS • COMPARISONS LOOK FOR DIFFERENCES • DIFFERENCES CAN BE FOUND • BETWEEN A GROUP OF PEOPLE IN A PROGRAM WITH TEHMSELVES, BEFORE AND AFTER OR BEFORE DURING AND AFTER • BETWEEN A GROUP OF PEOPLE IN A PROGRAM AND A GROUP OF PEOPLE NOT IN A PROGRAM • BETWEEN A GROUP OF PEOPLE IN A PROGRAM AND A COMPARISON STANDARD (STATISTIC)

5. IN OUTCOME EVALUATIONS, THE DIFFERENCES WE LOOK FOR ARE • ON SPECIFIC OUTCOMES • EACH OUTCOME IS OPERATIONALIZED SO THAT I CAN MEASUSRE IT • WHEN I MEASURE AN OUTCOME, I COMPARE IT TO • THE CONDITION OF THE OUTCOME BEFORE THE PROGRAM • THE CONDITION OF THE OUTCOME IN ANOTHER GROUP • THE CONDITION OF THE OUTCOME AS SET BY A COMPARISON STANDARD

6. STATISTICAL TESTS MAKE THESE COMPARISONS FOR US. • EACH COMPARISON IS BASED ON • THE LEVEL OF MEASUREMENT FOR THE OUTCOME • WHETHER IT IS LOOKING FOR A DIFFERENCE (THIS IS USUALLY THE CASE IN OUTCOME EVALUATIONS ) OR AN ASSOCIATION BETWEEN OUTCOMES (RARER) • THE TYPE OF DESIGN WHICH DETERMINES HOW COMAPRISON ARE MADE • HOW MANY COMPARISONS ARE MADE

7. So how do I know which statistical analyses to use? This question is not as difficult to answer as you think; provided you have followed the last three weeks. IF YOU HAVE FOLLOWED THE LAST THREE WEEKS, YOU HAVE ALL OF THE INFORMATION THAT YOU NEED TO ANSWER THIS QUESTION EXCEPT WHAT LEVEL OF MEASUREMENT AM I USING?

8. *****RESEARCH REVIEW***** LEVEL OF MEASUREMENT REFER TO THE MEASUREMENT SYSTEM BEING USED IN THE RESEARCH. Lets look at the following EXAMPLES: NOMINAL MEASUREMENT SUPPOSE I GAVE AN EXAM OF 50 QUESTIONS AND EACH WAS WORTH 2 [POINTS. THAT MEANS THE PERFECT SCORE WOULD BE 100 POINTS AND THE WORST SCORE (POTENTIALLY) WOULD BE 0 POINTS. SO I GIVE THE TEST! ALTHOUGH I SCORE IT – LOWEST SCORE WAS 50 AND THE HIGHEST WAS 96 = I AM MORE INTERESTED IN SEEING HOW MANY PEOPLE PASSED AND HOW MANY PEOPLE FAILED. ALTHOUGH STUDENTS MIGHT BE VERY INTERESTED IN THEIR SCORES I AM MORE INTERESTED IN HOW MANY ARE PASSING AND NOT PASSING. I CAN REMEMBER THIS! CATEROGRIES ARE ALWAYS SIMPLER FORMS OF MEASUREMENT. I.E. PASSED FAILED

9. SO NOW I HAVE 2 CATEGORIES 1. = PASSED. 2. = FAILED Lets say say out of 30 people, 23 passed and 7 failed. So Passed = 23; failed = 7. 2. Lets say I want to know how many people are graduating from the msw concentration class. There are essentially two categories 1. = graduated. 2. = did not graduate. 3. Lets now say, I want to know the political affiliations of students. I begin to ask them what they are. (of couse, at first – being the stupid person I am – I assume that I will have 2 categories; 1. = republican; 2. = democrat. However, in taking my poll, I find that several student declare that they are ‘independents’ and have no party affiliation and two students declare that they are members of the ‘socialist party’. So now I realize that I have 4 categories. 1 = republican, 2 = democrat, 3. = independent, 4. = socialist. Sometimes categories come already defined. Examples are Race/ ethnicity (Euro American, African American, Hispanic American, asian american, native American etc) gender (male/female) sexual preference (homosexual, heterosexual, bi-sexual).

10. AT THIS LEVEL OF MEASUREMENT CATEGORIES ARE USED TO MEASURE! SOMETIMES THESE ARE REFERRED TO AS ‘CATEGORICAL VARIABLES’. THE LEVEL OF MEAUREMENT THAT USES CATEGORIES IS CALLED NOMINAL (REFERRING TO ‘NAMES FOR THINGS’) WHEN CATEGORIES ARE USED IN PROGRAM EVALUATIONS, THEY OFTEN TAKE THE FORM OF THINGS LIKE COMPLETED PROGRAM - DID NOT COMPLETE SATIFIED – DISSATISFIED ATTENDED – DID NOT ATTEND VERY SUCCESSFUL – MODERATELY SUCCESSFUL –UNSUCCESSFUL VERY GOOD – GOOD – O.K. – NOT SO GOOD –BAD –VERY BAD A – B – C- D – E – F Consistent parenting, inconsistent parenting, inappropriate parenting

11. AS YOU CAN SEE YOU CAN HAVE A NUMBER OF CATEGORIES ALTHOUGH HAVING MORE DEFEATS THE PURPOSE BECAUSE CATEGORIES ARE THE SIMPLEST FORM OF MEASUREMENT (SO TOO MANY CATEGORIES CAN BECOME CONFUSING). THUS I AM MEASURING DATA BASED ON A PARTICULAR QUALITY (TEST SUCCESS, ETHNICITY, ATTENDENCE, POLITICAL AFFILIATION, PARENTING ABILITY ETC.) AND THE CATEGORY THAT DATA FALL INTO WITHIN THAT QUALITY! NOTICE THAT WITH CATEGORICAL MEASUREMENT, YOU CAN BELONG ONLY IN ONE CATEGORY!!!! Categoric variables are almost always the independent variables in research –when doing comparisons: • male female • received treatment (experimental group) did not receive treatment (control group) • msw students, counseling students, sociology students • non-licensed msw’s, lmsw’s, lcsw’s

12. ORDINAL MEASUREMENT LETS GO BACK TO SOME PREVIOUS EXAMPLES: 1. SUPPOSE I GAVE AN EXAM OF 50 QUESTIONS AND EACH WAS WORTH 2 [POINTS. THAT MEANS THE PERFECT SCORE WOULD BE 100 POINTS AND THE WORST SCORE (POTENTIALLY) WOULD BE 0 POINTS. SO I GIVE THE TEST! ALTHOUGH I SCORE IT – LOWEST SCORE WAS 50 AND THE HIGHEST WAS 96 = RATHER THAN SEEING HOW MANY PASSED, I WANT TO RANK THE STUDENTS FROM HIGHEST TO LOWEST GRADES. SO NOW IF I HAVE 30 STUDENTS I WILL HAVE AN ORDER IN WHICH I AM NOT COUNTING PASSED/FAILED OR THE ACTUAL SCORES BUT AM COUNTING THE ORDER TO THE RANKING OF SCORES FROM HIGHEST TO LOWEST 2. Lets say I want to know WHO IS GRADUATING FIRST IN THEIR MSW CLASS AND WHO IS GRADUATING LAST. I WOULD LOOK AT THE GPA AND RANK THEM FROM HIGHEST TO LOWEST. Lets now say, I want to know WHO VOTES THE MOST BETWEEN REPUBLICAN AND DEMOCRATS! I MIGHT INTERVIEW PEOPLE AND 1. ASK THEM THEIR POLITICAL AFFILIATION AND 2. ASK THEM HOW MANY TIMES THEY VOTED IN THE LAST YEAR. NOW, I PUT ALL OF THEM TOGETHER AND ‘RANK’ THEM IN THE ORDER OF WHO VOTES MOST TO VOTED LEAST. THEN I LOOK AND SEE IF THERE ARE MORE REPUBLICANS OR DEMOCRATS AT THE TOP OF THE LIST. THUS I AM MEASURING BASED ON THE POSITION OF INDIVIDUAL DATA WITHIN THE DATA SET THIS TYPE OF MEASUREMENT BY RANKING IS KNOWN AS ORDINAL! MOST OF THE TIME, THIS TYPE OF MEASUREMENT IS NOT USED UNLESS I AM RANKING A NUMBER OF PROGRAMS

13. THIS IS THE TYPE OF MEASUREMENT MOST OF YOU WILL USE FOR YOUR DEPENDENT VARIABLES! INTERVAL MEASUREMENT INTERVAL MEASUREMENT IS A SYSTEM OF MEASUREMENT BASED ON THE ‘SPACING BETWEEN” POINTS OF MEASUREMENT. THIS SYSTEM REQUIRES THAT ALL OF THE INTERVALS ARE EQUAL!!! FOR EXAMPLE, AGE IS A FORM OF INTERVAL MEASUREMENT(THE DIFFERENCE BETWEEN 54 AND 53 AND BETWEEN 11 AND 12 IS ALWAYS THE SAME; ONE YEAR. LIKEWISE THE DIFFERENCE BETWEEN 48 DEGREES AND 58 DEGREES IS THE SAME AS THE DIFFERENCE BETWEEN 10 DEGREES AND TWENTY DEGREES. MORE RELEVANTLY, SUCH THINGS AS ‘DAYS SPENT IN A HOSPITAL, NUMBER OF HOSPITALIZATIONS, # OF TRIPS TO THE PRINCIPAL’S OFFICE, NUMBER OF INCIDENTS OF POOR PARENTING, NUMBER OF REPORTS TO DFCS ARE ALL INTERVAL MEASURES. SO TOO ARE CONSTRUCTED MEASURES SUCH AS SCORES ON THE BECK’S DEPRESSION INVENTORY, SCORES ON MY EXAMS ETC. LETS GO BACK TO OUR EXAMPLES

14. 1. SUPPOSE I GAVE AN EXAM OF 50 QUESTIONS AND EACH WAS WORTH 2 POINTS. THAT MEANS THE PERFECT SCORE WOULD BE 100 POINTS AND THE WORST SCORE (POTENTIALLY) WOULD BE 0 POINTS. SO I GIVE THE TEST! THE SCORES ‘RANGE’ FROM 50 POINTS TO 96 POINTS. BECAUSE THE (THEORETICAL) DISTANCE BETWEEN EACH POINT IS THE SAME, THE ‘VARIANCE’ BETWEEN SCORES OF 55 AND 50 AND SCORES OF 40 AND 45 IS THE SAME (5 POINTS). BECAUSE OF THIS VERY COOL PRINCIPLE IN INTERVAL MEASUREMENT - WHERE THE DISTANCE BETWEEN EACH UNIT OF MEASUREMENT AND THE UNIT NEXT TO IT IS ALWAYS THE SAME – IT ALLOWS US TO DO SOME NEAT THINGS LIKE, CALCULATE MODES, COMPARE MEAN SCORES, ANALYZE VARIANCE, CALCULATE CORRELATION COEFFICIENTS ETC. THUS I COULD COMPARE THE MEAN SCORES OF MALES AND FEMALES ON THE EXAMS OR THE MEAN SCORES OF FACE TO FACE AND WEB STUDENTS Lets say I want to know WHO IS GRADUATING AND HOW THEY STACK UP WITH EACH OTHER OR PAST GRADUATING CLASSES. BECAUSE GRADE POINT AVERAGE IS AN INTERVAL MEASURE, I COULD COMPARE THE MEAN G.P.A.s OF FACE TO FACE CLASS WITH THE WEB CLASS, OR THIS YEAR’S GRADUATING CLASS WITH LAST YEARS AND THE YEAR BEFORE (AND MANY OTHER YEARS IF I WANT). INTERVAL MEASUREMENT IS THE MOST OFTEN USED IN RESEARCH AND IS PROBABLY THE ONE YOU WILL BE USING WITH YOUR DEPENDENT VARIABLES. ****END OF REVIEW****