4TH LESSON Random Sampling Stats and Pr.

Random Sampling

1. Random Sampling

2. Illustrates random sampling; LEARNING OBJECTIVES distinguishes between parameter and statistic; identifies sampling distributions of statistics (sample mean); finds the mean and variance of the sampling distribution of the sample mean.

3. The Less, the Merrier Group the class into two with equal group members. We have two cards here, draw a card. The group will have to divide the members according to the subgroups of the category. The group will have to divide the members according to the subgroups of the category. Answer the questions that follow.

4. Why is creating a subgroup important? Give another category and subgroups that can be formed that apply to the whole class. Ex. Gender What are the different groups to which you can divide a population composed of senior high school students?

5. Sampling I know you have your “Practical Research” subject. What comes into your mind whenever you heard the word “SAMPLING”.

6. DEFINITION OF TERMS: In modern statistics, the main object to be analyzed is data. Sample - part/portion/fraction/segment of the population being studied. Population - the whole universe or consists of all elements or totality of things considered in a study.

7. DEFINITION OF TERMS: Survey – method of systematically gathering of information Sample survey - method of systematically gathering of information on a segment/part/fraction/portion of a population for the purpose of inferring quantitative descriptors of the attributes of the population

8. DEFINITION OF TERMS: Sampling - process of selecting a section of the population Random – the outcome is obtained only by chance

9. DEFINITION OF TERMS: Random Sampling – method of choosing an equally distributed subset/portion from a larger population to be used as basis in describing or making conclusions about the population. Statistical Inference - process of using sample statistics to draw conclusions about true population parameters

10. TWO TYPES OF SAMPLING Probability Sampling It is a sampling method that allows every member of the population to have an equal chance of being selected into the sample.

11. DRAWLOTS Get 1/8 piece of paper, write your name. I will pick 5 learners who will have a recitation chip.

12. Basic Type of Probability Sampling Simple random sampling (SRS) involves allowing each possible sample to have an equal chance of being picked and every member of the population has an equal chance of being included in the sample.

13. Simple random sampling (SRS) with replacement (selected individual or unit is returned to frame for possible reselection). without replacement (selected individual or unit is not returned to the frame).

14. Simple random sampling (SRS) This sampling method requires a listing of the elements of the population called the sampling frame .

15. Basic Type of Probability Sampling Stratified sampling is an extension of simple random sampling which allows for different homogeneous groups, called strata, in the population to be represented in the sample.

16. GROUP YOURSELVES I will state a category and group yourselves according to that category.

17. Stratified sampling To obtain a stratified sample, the population is divided into two or more strata based on common characteristics. A SRS is then used to select from each strata, with sample sizes proportional to strata sizes. Samples from the strata are then combined into one.

18. Basic Type of Probability Sampling Systematic sampling elements are selected from the population at a uniform interval that is measured in time, order, or space. Typically, there is firstly, a decision on a desired sample size n. The frame of N units is then divided into groups of k units: k=N/n. Then, one unit is randomly selected from the first group, with every kth unit thereafter also selected.

19. Basic Type of Probability Sampling Systematic sampling Formula: k=N/n where: K= systematic sampling interval N=population size n=sample size

20. Basic Type of Probability Sampling Systematic sampling Example: There are 100 math students, take a systematic sample of size n=5. What is the systematic interval?

21. Basic Type of Probability Sampling Cluster sampling divides the population into groups called clusters, selects a random sample of clusters, and then, subjects the sampled clusters to complete enumeration, that is everyone in the sampled clusters are made part of the sample.

22. GROUP ACTIVITY Group into 4. Pick an instruction card. Do the assigned tasks.