Statistics Notes PDF

Statistics is a branch of mathematics that deals with collecting, organizing, and interpreting data to address a certain phenomenon. Example: Marketing strategists use statistics to see the current market trend and devise solutions on how companies could sell more of their products. Population is...

Statistics is a branch of mathematics that deals with collecting, organizing, and interpreting data to address a certain phenomenon. Example: Marketing strategists use statistics to see the current market trend and devise solutions on how companies could sell more of their products. Population is the set of all possible cases from which data are collected. Example: A study regarding the average height of students in a school requires the set of all students studying in that school as its population. Sample is a subset of the population under study. Example: A study regarding the average height of students in a school may focus only on the sample set of students in a single grade level studying in that school. Variables are characteristics that vary over time from subject to subject. Example: Consider a study regarding the influence of social media on students’ preferences in choosing a student leader. In this study, a researcher may include the number of social media accounts per sample student as one of the variables. The researcher can also choose the gender of the sample student as another variable.  The relationship between social media use and mental health outcomes in adolescents. The relationship between parenting style and childhood obesity. The relationship between personality traits and job performance in high-stress occupations. The effectiveness of family therapy in improving communication and Qualitative Variable is a type of variable that focuses on the quality or characteristics of each experimental unit. Example: Civil Status, Gender, Color, Favorite Movie Quantitative Variable is a type of variable that measures a numerical quantity on each experimental unit. Example: Age, Height, Weight, Daily Allowance 7. Data Collection is the process of gathering data such as surveys, interviews, etc. 8. Sampling technique is the PROCESS of selecting subset of the population.  DATA – information that is collected for analysis/studies Classification of Data 1) Qualitative Data - refers to categorical data or descriptive attributes. Example/s: Gender, Color, Physical Traits, Citizenship 2) Quantitative Data - refers to numerical information Qualitative Data-is a type of variable that focuses on the quality or characteristics of each experimental unit. 1. Since our country is infected with Corona Virus, do you follow the health protocols given by the Department of Health? 2. Favorite milk tea flavor. 3. Preferred color based on the meaning of it. (e.g. Blue signifies calmness, tranquility, relaxation and peace.) Quantitative Data - is a type of variable that measures a numerical quantity on each experimental unit. A. Discrete Data -are those in numerical form. -a variable that may assume only a countable, and usually finite, number of values. 1. Number of boys and girls in grade 7 per section Eridanus 2. The result of rolling 3 dice 3. The number of books in the shelves Quantitative Data B. Continuous Data -are measurements that can take any value from an infinite range. 1. The heights of all grade 7 students 2. Age of a persons 3. Distance travelled by an airplane overtime.  5 Methods in Collecting Data 1. Interview or Direct Method 2. Questionnaire or Indirect Method 3. Observation Method 4. Experiment Method 5. Registration Method  METHODS IN COLLECTING DATA 1) Direct or Interview Method It is used in conducting surveys. It is done when a person solicits information from another person either by telephone or in-person. The interviewer is the person gathering the data, while the interviewee is the person being interviewed. Example: A certain telecommunication company would ask a caller to rate their services after the latter questions about her  METHODS IN COLLECTING DATA 1.1) Focus Group Discussion (FGD) - it is used to know the thinking, feeling or opinion, about a certain phenomenon, idea and etc. FGD is conducted with a small group of people with common knowledge and common field (usually 6 to 8 people).  METHODS IN COLLECTING DATA 2) Indirect or Questionnaire Method It is used in conducting surveys. It is done by reproducing a printed questionnaire, which is a checklist of prepared questions, and distributed to individuals needed to be studied depending on the content of the questionnaire. The individuals then answer the questionnaire and return it to the researcher Example: Customers in a restaurant were given a printed checklist to rate the food  METHODS IN COLLECTING DATA 2) Indirect or Questionnaire Method Types of Questions a. Closed questions These are questions which can be answered with “Yes” or “No,” or they have a limited set of possible answers (such as: A, B, C, or All of the above). For example, ‘Do you wear glasses?’ the respondent either does (responding ‘yes’) or doesn’t (responding ‘no’) wear glasses.  METHODS IN COLLECTING DATA b. Open-ended questions These are questions that allow someone to give a free-form answer. Example, “How did you answer the modules?” c. Multiple-choice questions These are questions that provide a certain number of specific response options as possible answers. An example of multiple-choice question would be: “How do you spend your free time?”. a. reading d. watching TV b. listening to radio e. others (please specify: __)  METHODS IN COLLECTING DATA 3) Observation Method In this method, the researcher observes the behavior of the participants. The investigator is the person gathering the data, while the subject is the person being observed. It makes use of the human senses. Example: A researcher would like to know the effect of too much water and sunlight on certain plants.  METHODS IN COLLECTING DATA 4) Experiment Method It is used to determine the cause-and-effect relationship of certain phenomena under controlled conditions Example: Researchers would make some tests to determine which vaccine will be more effective to be immune from the virus before releasing it to the public.  METHODS IN COLLECTING DATA 5) Registration Method In this method, information can be gathered from documents or reports which are released by the government or any institution Example: The researcher will identify the number of cases, recoveries, and deaths of COVID-19 in a day as reported by the Department of Health (DOH).  5 Sampling Techniques 1. Random Sample 2. Convenience Sample 3. Stratified Random Sample 4. Cluster Sample 5. Systematic Sample  Types of Sampling Techniques 1. Random Sample - each member of the population has an equally likely chance of being selected. The members of the sample are chosen independently of each other. 2. Convenience Sample - is a sample that is chosen so that it will be easy for the researcher. 3. Stratified Random Sample - the population is divided into subgroups, so that each  Types of Sampling Techniques 4. Cluster Sample - is a sample that consists of items in a group such as a neighborhood or a household. The group may be chosen at random. 5. Systematic Sample - is obtained using an ordered list of the population, thus selecting members systematically from the list.