Give the classification of surveys.

A survey is a research method used to collect data from a sample of respondents to obtain information about the characteristics, actions, or opinions of a larger population. Surveys can be classified into different categories based on various factors such as purpose, data collection method, and time frame.

Surveys can be classified into three main categories based on their purpose: 1. Descriptive surveys: These surveys aim to describe the characteristics of a population, such as attitudes, opinions, behaviors, or demographics. 2. Exploratory surveys: These surveys are designed to explore new topics or generate hypotheses. They are often used in the early stages of research to gather initial information on an unknown subject. 3. Explanatory surveys: These surveys try to identify relationships or causality between variables. They are used to test hypotheses or theories and can provide insight into why certain trends, behaviors, or relationships exist.

Surveys can also be classified based on the method of data collection: 1. Self-administered surveys: In this type of survey, respondents complete the questionnaire themselves, either on paper or electronically. Examples: online surveys, mail surveys, and drop-off surveys. 2. Interviewer-administered surveys: In these surveys, an interviewer asks the questions and records the answers. There are two main types of interviewer-administered surveys: a) Face-to-face (or personal) interviews: The interviewer conducts the survey in person, typically in the respondent's home or at a central interviewing facility. b) Telephone interviews: The interviewer conducts the survey over the phone and records the respondents' answers.

Another way to classify surveys is by their time frame: 1. Cross-sectional surveys: These surveys collect data at one point in time from a sample of the population. The main goal is to provide a snapshot of the population at a given moment. 2. Longitudinal surveys: These surveys collect data from the same sample of respondents over time, allowing researchers to observe changes or trends in the population. There are three main types of longitudinal surveys: a) Panel surveys: Data is collected from the same individuals or households over time, providing information on the changes that occur within those groups. b) Cohort surveys: Data is collected from a specific group of people (cohort) who share a defining characteristic, such as age, location, or graduation year. Cohort surveys focus on changes within the cohort over time. c) Trend surveys: Data is collected from different samples of the same population at different points in time. Trend surveys focus on changes in the overall population instead of individual changes. By understanding these different classifications of surveys, we can better grasp the various research purposes and data collection methods employed in survey research.