a) Census: A census is a comprehensive data collection method that involves gathering information from every individual or unit within a certain population. Unlike surveys that collect data from a smaller sample, a census aims to achieve complete accuracy by covering the entire demographic. This process is often conducted at regular intervals, such as every ten years in many countries, to assess population characteristics, social factors, and economic conditions.
b) Parameter: A parameter is a numerical characteristic or measure that describes an entire population. It can represent various aspects such as mean, median, or proportion. Understanding parameters is crucial because they provide a basis for comparison when analyzing data. However, since it is often impractical to measure an entire population, researchers rely on statistics from samples to estimate parameters.
c) Statistic: A statistic is a numerical value that describes a sample and is used to estimate a corresponding parameter of the population from which the sample is drawn. Statistics help researchers make inferences about populations based on representative samples. For example, the average height of students in a school can be considered a statistic, while the average height of all students in a country would be the corresponding parameter.
d) Bias: Bias refers to systematic errors that can lead to incorrect conclusions in data collection or analysis. It can originate from various sources, such as the way a survey is conducted, selection of the sample, or the framing of questions. Bias undermines the validity of research findings and can distort the true representation of the population. Identifying and minimizing bias is essential for ensuring the reliability of any statistical analysis.