In other words, when the total number of people characterized by each variable (or stratum) oscillates within the population, to the researcher would choose the size of each sample for each stratum according to the research requirements. Such a choice is prejudiced by the probability of obtaining an adequate number of sampling units from each stratum within the final sample. As a rule, disproportionate stratified samples are used either to compare two or more particular strata or to analyze one stratum intensively (Creswell, 1994). Therefore, when researchers use a disproportionate stratified sample, we have to weight the estimates of the population's parameters by the number of units belonging to each stratum. In this sample, weighting strategies were not performed in the original data. Once researchers have defined the population of interest, they draw a sample that adequately represents that population. The actual procedure involves selecting a sample from a sampling frame encompassing a complete listing of sampling units. Preferably, the sampling frame should consist of all the sampling units in the given population. However, in practice, such information is rarely available. For this reason, researchers usually use substitute lists that contains the same information but may not be comprehensive. In addition, there is a high degree of correspondence between a sampling frame and sampling population. The exactness of the sample depends, primarily, on the sampling frame, because every aspect of the sample design -- the population covered, the stages of sampling, and the actual selection process -- is influenced by the sampling frame. Prior to selecting a sample, the researcher must evaluate the sampling frame for potential problems. According to Kish, when inspecting the sampling frame, the characteristic problems found in sampling frames are as follows:

1. Incomplete frame. The problem of incomplete sampling frames occurs when sampling units present in the population are absent from the list. If the researcher finds that the sampling frame is incomplete, one option that might be available is the use of supplemental list. In this data, schools are sampled from the complete sampling frames, incomplete sampling frames does not exist in this sample.

2. clusters of elements, The second potential type of problem with sampling frame is clusters of elements. This problem occurs when the sampling units are listed in group rather individually. In this sample, this problem does not exist.

3. blank foreign elements. The third potential type of problem is blank foreign, which is quite common in studies. It occurs when some of the sampling units in the sampling frame are not part of the research population, such as the case where the research population is defined as eligible voters whereas the sampling frame includes individuals who are too young to vote. This problem often occurs when outdated lists are used as the sampling frame. In the current survey, this problem of blank foreign elements does not applied in this data.

Compared to a clinical, convenience or purposive sample, the sample for the current study is more generalizable by capturing a wide spectrum of data on teachers' corporal punishment of students in schools and students' responses with a range of victimization experiences. The study also reaches students who have not sought outside assistance for various reasons. Most importantly, it investigates many schools in rural areas, where there are less educational resources, compared to the area of Northern Taiwan which is more urbanized and rich in resources. Thus far, many studies have been conducted in the North but much fewer in Central or Southern regions. This data can aid us in understanding the current teachers' corporal punishment issues in these areas, which have more vulnerable educational systems.

Overall, such data is more representative nationally based on a stratified sampling method. The sampling approach also includes the students from rural or other areas in Taiwan that are often ignored by many researchers. Seemingly, using this sampling method, we can more accurately estimate the prevalence of teachers' employing corporal punishment on students. In addition, the victimization rate is more representative, and there are no prblems associated with sampling frames, which strengthens the confidence of this data. Since a high response rate (97%) is achieved in this data, it can be perceived as very representative of the overall population. However, because only elementary and junior high schools in Taiwan were sampled, the results of this study can only be generalized concerning the elementary and junior high schools in Taiwan. Senior high schools would not be part of the generalization, and the results may not be generalized to other countries in the world.

Instrument

A self-created version of Teachers' Aggressive Punishment toward Students (Human Education Foundation, 2004) was administered to measure the variables of interested in this study. This instrument was composed of 42 items. The content of this instrument is as follows:

Basic Demographic Information. Four items provided demographic information, such as the location where students were located (North, Central, South; Urban and Rural), students' gender, and students' "I saw teachers asking students to strike other students as punishment,"

"I saw teachers directly hitting students,"

"I saw teachers depriving students' basic needs, such as eating, drinking, resting."

These questions were answered by 1=no and 2=yes. The scale had an alpha reliability of .78. The second part is the variable examining what students saw as the tools that teachers used when they punished students. The question is "What tools have you seen since last semester that teachers used when they punish students?" There are 7 items and include, for example,

"Did you see that teachers use their hand to aggressively punish students? ,"

"Did you see teachers using ruler to punish students?"

"Did you see teachers using rod to punish students?"

Responses given were 1=no, and 2 = yes. The scale had alpha reliability of .77.The third part of this scale is the open question. The question is designed to discover if any out of the ordinary punishment tools or methods were employed by teachers in schools. Students are asked, "What are the most strange or weird implements and ways that teachers employ when they punish students?" Students are asked to provide a brief description of what they saw.

Prevalence of Punishment. This instrument is a subscale consisting of three questions that refer to the students' personal experience on teachers' administration of corporal punishments.

First item is "What proportion do you think among your teachers physically punished students since last semester?" The responses were given in a 4-point Likert-type by 1= all of them, 2= over a half, 3= below a half, and 4= none.

The second question is "How many times have you been physically punished by teachers since last semester?" The responses were given in a 4-point Likert-type with 1= never, 2= 1 to 5 times, 3= 6 to 10 times, and 4= over 10 times.

The third question is "Have your teachers asked your parents to sign the contract to permit physical punishment?" The response is given 1= yes, 2= no, and 3= don't know.

The reason of punishment. The fourth subscale is composed of 6 items that refer to the reasons why teachers in school punished students. The first five items are

" I was punished by teachers due to poor academic performance,"

"I was punished by teachers due to behavior problems,"

"I was punished by teachers due to bad attitude,"

"I was punished by teachers due to fighting with other students," and " I was punished by teachers for being associated with other students who have committed an offence."

The sixth question allows an open answer so student could describe other reasons why they were punished. Responses of the first five items were given on 1= no and 2 =yes. These five items had an alpha reliability coefficient of .63.

Impact of Punishment. The goal of this subscale is to examine the impact of teachers' punishment on students. Two dimensions were inspected and the first dimension was to examine the impact of direct punishment. Students were asked about their thoughts when punished by teachers, and the items included the following

"I feel scared, shamed, and quilt,"

" I feel angry and want to retaliate"

" I feel I deserved the punishment"

" I think it is cruel and unreasonable treatment"

" I feel I am the target of the teachers' venting their frustration," and " I don't know."

The last question is open to allow students to describe their feeling or thoughts. The six items were given responses of 1=no, and 2= yes. The first six items had an alpha reliability coefficient of .82.

The second dimension was to examine the impact of witnessing teachers' punishment of other students. Students were asked, "When you see other students punished by teachers, what do you think?" Answers included

"I feel sympathy toward those students,"

" I feel…