SINGLE VARIABLE DATA

DEFINITIONS ETC

GENERAL STUFF

•STATISTICS IS THE PROCESS OF GATHERING, DISPLAYING, AND ANALYZING DATA.

•DATA CAN BE GATHERED BY CONDUCTING AN EXPERIMENT OR A SURVEY.

SAMPLING TECHNIQUES•WHEN CONDUCTING A SURVEY, CHOOSE APPROPRIATE QUESTIONS THAT

SATISFY THE SURVEY’S REQUIREMENTS AND CHOOSE A REPRESENTATIVE POPULATION.

•IN MARKET RESEARCH AND DEVELOPMENT (R AND D), A TARGET GROUP IS CHOSEN TO ADMINISTER THE SURVEY.

•YOU WOULDN’T TRY TO MARKET AXE™ BODY SPRAY TO SENIOR CITIZENS; IT’S NOT THE TARGET DEMOGRAPHIC FOR SALES

•IT’S NOT PRACTICAL TO SURVEY AN ENTIRE POPULATION SO A SAMPLE IS CHOSEN.

HOW TO CHOOSE A SAMPLE•SIMPLE RANDOM SAMPLE: EACH MEMBER OF THE

POPULATION HAS AN EQUAL CHANCE OF BEING SELECTED.

•STRATIFIED RANDOM SAMPLE: THE POPULATION IS DIVIDED INTO SUBGROUPS (GENDER, AGE, ETC) AND THEN A RANDOM SAMPLE IS PICKED FROM EACH SUBGROUP BASED ON THE POPULATION DISTRIBUTION OF THE SUBGROUPS.

•VOLUNTARY-RESPONSE SAMPLE: CONTAINS MEMBERS OF THE POPULATION THAT CHOSE TO RESPOND TO THE SURVEY.

HOW TO CHOOSE A SAMPLE•CLUSTER SAMPLE: THE POPULATION IS DIVIDED INTO

CLUSTERS AND THEN A CERTAIN NUMBER OF CLUSTERS IS CHOSEN. THE SAMPLE CONTAINS EVERY MEMBER OF A CLUSTER.

•CONVENIENCE SAMPLE: THE SAMPLE CONTAINS MEMBERS OF THE POPULATION EASILY ACCESSED TO OBTAIN DATA.

•SYSTEMATIC SAMPLE: EVERY NTH MEMBER OF THE POPULATION IS SELECTED.

BIAS IN SAMPLING TECHNIQUES•IF THE RESULTS OF A SURVEY DO NOT REFLECT THE

POPULATION, THE SURVEY HAS BIAS.

•BIAS MAY BE INTRODUCED BY A POOR SAMPLE CHOICE, POOR SURVEY WORDING, OR HOW THE RESULTS ARE PRESENTED.

•THERE ARE MANY SAMPLING TECHNIQUES, EACH WITH STRENGTHS AND WEAKNESSES.

•THE CHOICE OF THE SAMPLING TECHNIQUE DEPENDS ON THE TARGET POPULATION AND THE TYPE OF SURVEY CONDUCTED.

EXAMPLE•EX) YOU WISH TO SURVEY HAMILTON HIGH SCHOOLS TO FIND

OUT THEIR FAVOURITE BAND THEY LISTEN TO. YOU HAVE A FRIEND AT ANOTHER HAMILTON HIGH SCHOOL AND YOU EACH CONDUCT THE SAME SURVEY AT EACH SCHOOL WITH SOME STUDENTS. YOU USE THESE RESULTS TO MAKE CONCLUSIONS.

•IDENTIFY THE POPULATION AND THE SAMPLE.

•IS THE SAMPLE REPRESENTATIVE? WHY OR WHY NOT? HOW MIGHT IT BE CHANGED TO MAKE IT BETTER?

ANSWERS•POP: ALL HIGH SCHOOL STUDENTS IN HAMILTON. SAMPLE: STUDENTS SURVEYED FROM 2 SCHOOLS

•THERE ARE ABOUT 15 HIGH SCHOOLS IN HAMILTON. THE STUDENTS THEY CHOSE MIGHT BE FAIR FOR A SAMPLE OF THOSE 2 SCHOOLS BUT MORE SAMPLES WOULD BE NEEDED TO INCLUDE ALL HAMILTON HIGH SCHOOLS. DO WE INCLUDE SUBURBS? SEPARATE SCHOOLS? PRIVATE SCHOOLS? THIS SAMPLE SIZE IS TOO SMALL TO DRAW PROPER CONCLUSIONS FOR ALL HAMILTON HIGH SCHOOLS.