>> Hello everyone. In this segment we will discuss variables and data. Once we have collected a set of measurements, we will first need to answer questions back, how can we display this set in a clear, understandable, and readable form? Before displaying sets of measurements, we will define what is meant by measurements and data. What is meant to categorize the types of data that we are likely to see in real life? Now we'll begin by introducing some important terminology. A variable is a characteristic that changes or varies over time for different individuals or object under consideration. For example, hair colour is a variable that's varies from person-to-person. An experimental unit is the individual or object on which a variable is measured. A single measurement results when a variable is actually measured on an experimental unit. While hair colour is considered to be a variable that's varied from person-to-person. A person is an experimental unit. What is data? Data is individual pieces of information. So we may say that data is a set of values of qualitative and quantitative variables. It is measured, collected, and reported and analysed where upon it can be visualized using graphs or images. Univariate data results when a single variable is measured on a single experimental unit. Bi-varied data results when two variables are measured on a single experimental unit. For example, if we measure scores of say, 50 students on a single math test, the resulting data are univariate. If we measure math mid-term and final exams of these students, then they are bivariate. Multivariate data results when we measure more than two variables. Now I will discuss types of data. Data are divided into two groups. Qualitative and quantitative. Qualitative variables measure a quality or characteristic of each experimental unit. For example, hair colour -- black, brown, blonde -- is a qualitative variable. Quantitative variables measure a numerical quantity or amount on each experimental unit. Also, quantitative data are divided into two groups. A discrete quantitative variable can assume only a finite or countable number of values. For example, number of oranges is a discrete, quantitative variable. A continuous quantitative variable can assume the infinite amount of variables corresponding to the points on a line interval. Time responded question is a continuous quantitative variable. Please check your knowledge by answering the questions provided to you in the first module.