Descriptive statistics deal with obtaining sample(s), subsample(s), or population(s) of data. They also provide information and opinions necessary to understand and explain information. In addition, they involve the measurement of central tendency, skewness, and distribution shape relative to or in relation to a population. One of the most common descriptive statistics is the average, a central point of data from a population. Other common descriptive statistics include median, standard deviation (see Standard deviation), and coefficient of variation (see The coefficient of variation). The distribution of data can describe the spread (or dispersion) of data around the mean or median. Common measurements are the range, variance, standard deviation, skewness and kurtosis.
Statistics are not a precise art. Despite the appearance of certainty within statistics, it is usually only probable that the results can be trusted. The wide use of statistics in modern society is the result of their incomplete certainty. We live in a fallible world where individuals make inaccurate measurements, journals of statistics are full of errors, and the statistical process itself is flawed with a tendency to give too much weight to chance. There is nothing like the widespread use of statistics to make the basic assumptions of empirical data-gathering vulnerable to scrutiny.
There are no strict rules about exactly who must participate in a statistical study, the scope of the study, the ways in which data is collected, nor on best practices for collecting and analyzing data. Many studies are either observational or experimental. Observational... studies collect data without manipulating participants in any way. Experimental... studies manipulate participants in some way, such as by randomly assigning participants to experimental groups or using some other variant of a controlled experiment. Some are quasi-experimental, which alter, but not manipulate, a phenomenon. Quasi-experimental... studies alter or manipulate a naturally occurring phenomenon and then collect data on the results. Randomized controlled experiment,... are the most commonly used methodologies. d2c66b5586