Random Sampling

• N = the number of cases in the sampling frame
• n = the number of cases in the sample
• _NC_n = the number of combinations (subsets) of n from N
• f = n/N = the sampling fraction

Simple Random Sampling

• The Effect of Using MURDER Technique to The Students’ Vocabullary achievement at First Year Student Of SMA Kartika Kendari.
• Objective: To select n units out of N such that each _NC_n has an equal chance of being selected.
• Procedure: Use a table of random numbers, a computer random number generator, or a mechanical device to select the sample.

First, we have to get the sampling frame organized. To accomplish this, we'll go through School Administration  to identify every Student at first year.Then, we have to actually draw the sample. Decide on the number of Student you would like to have in the final sample. For example, let's say we want to select 40 Students to survey and that there were 320 student of the first year. Then, the sampling fraction is f = n/N = 40/320 = .8 or 8%. To take the sample from the population we should follow some steps

1.      Make a random number (Table Random Number) in EXCEL by using this formula =INT(100000*RAND())+1, (it will random number 1 to 100000) then u will get table like this

2. In this case we have 320 population (N) and we will take 40 as our sample (n), to get our sample we just needed to make a line in hundred forms from the right, for example

61424, the hundred number that we will take is 424

3. If the hundred number that we take is ≤ 320 it will taken as our sample, but if the number ≥ 320 it will be eliminated, in this case we will take a hundred number that involves in our sample till we get 40 students as our sample. (we can see the example in EXCEL that already attached)

Stratified Random Sampling

Stratified Random Sampling, also sometimes called proportional or quota random sampling, involves dividing your population into homogeneous subgroups and then taking a simple random sample in each subgroup. In more formal terms:

• The Effect of Using MURDER Technique to The Students’ Vocabullary achievement at First Year Student Of SMA Kartika Kendari.
• Objective: Divide the population into non-overlapping groups (i.e., strata) N₁, N₂, N₃, ... N_i, such that N₁ + N₂ + N₃ + ... + N_i = N. Then do a simple random sample of f = n/N in each strata.
• Procedure: take n From N based on the strata or Proporsional

When we use the same sampling fraction within strata we are conducting proportionate stratified random sampling. It will generally have more statistical precision than simple random sampling. This will only be true if the strata or groups are homogeneous. If they are, we expect that the variability within-groups is lower than the variability for the population as a whole. Stratified sampling capitalizes on that fact.

For example, in this research we have 320 as our population and it devided into 8 class that begin from X.1 to X.8. based on the definition of stratified random sampling we will take sample from each class based on their proportion in pupolation. These are the procedure:

1. Decided the proportion for each class based on the number of population, for example, in X.1 class we have 41 students, from the total population (320), find out the percentage and the proportion of the class to the population. Look at the table below

STRATIFIED SAMPLING
KELAS	JUMLAH SISWA	PROPORSI (%)	PROPORSI(JUMLAH)
X.1	41	13	5
X.2	38	12	5
X.3	40	13	5
X.4	39	12	5
X.5	39	12	5
X.6	42	13	5
X.7	38	12	5
X.8	43	13	5
JUMLAH	320	100	40

If we already find the proportion of the population in this case is the count ( see the table above) then we just need to decided which one of each student who we want to take as a sample. In decided the sample we can use systematic random sampling for each class.

Cluster (Area) Random Sampling

• The Effect of Ethnic Ascent to The Students’ pronouncation at Kartika Senior High School
• Objective :  to find out the pronouncation of student based on their ethnic

In cluster sampling, we follow these steps:

• Divide population into clusters (based on their ethnic, Bugisnese, Tolakinese, Munanese, Butonese, and Javanese)
• randomly sample clusters
• measure all units within sampled clusters

in this case the population can be devided into group based on their ethnic,

For example conduct a research in Kartika Senior High School especially in First Grade class, If we do a simple random sample we'll have to cover the entire student in each class of the First Grade in Kartika. Instead, we decide to do a cluster sampling of Eight Class that have each ethnic, so we can get one class that will be our sample in this research. The research that we conduct will get intact class as our sample from the population. Clearly this strategy will help us to economize on our mileage. Cluster or area sampling, then, is useful in situations like this, and is done primarily for efficiency of administration.

Multi-Stage Sampling

• The Effect of Ethnic Ascent to The Students’ pronouncation at Kendari City
• Objective :  to find out the pronouncation of student based on their ethnic

(Kendari)

2 kota, 10 Kabupaten

10 kecamatan

SMA 1 KENDARI, SMA KARTIKA, SMA SATRIA, SMA OKUIMENE

SMA KARTIKA (X=8, XI=7, XII=7)

X=320 siswa

Sample 5 for each class