Math 1.1

• Most commonly used measures of central tendency. When we speak of getting the average, we always refer to the mean.
• Sample Mean - The sample mean is obtained by adding all the values in your sample and dividing by the sample size (which is usually denoted by small n).
• Population Mean If we were to calculate the mean from a population instead of a sample, then we would still proceed in the same way, we would add up all the values in the population (more values to add) and we would divide by the population size (denoted by N)
• The median of a set of data values is the middle value of the data set when it has been arranged in ascending order. That is, from the smallest value to the highest value.
• Mode is a statistical term that refers to the most frequently occurring number found in a set of numbers.
• MIDRANGE

  This is a rough estimate of the middle. It is found by getting the average of the lowest and highest value of the data.
• Weighted Mean - this is used to find the mean of values of the data set that are not equally represented.
• True: sometimes, the measures of central tendency alone are not sufficient to give useful information.
• Three measures of variation, namely, the range, variance, and the standard deviation.
• Measures of Variability these measures describe how item values cluster or scatter in a distribution.
• The simplest measure of dispersion is the range.
• The Range is the difference between the highest and the lowest values in the set of data 
• Variance-the measure of dispersion that removes negative signs by squaring all deviations of each number from its mean and getting the average of the squared deviations is the variance.
• The standard deviation is the most commonly used measure of variation.
• The standard deviation indicates how closely the values of a given data set are clustered around the mean.
• A lower value of the standard deviation means that the values of the given data set are spread over a smaller range around the mean.
• a large value of the standard deviation means that values of that data set are spread over a large range around the mean
• The mode is found by collecting and organizing the data in order to count the frequency of each result.
• The result with the highest occurrences is the mode of the set. The mode for grouped data is the modal class. If no number is repeated, then there is no mode for the list.
• The weighted average can be found by multiplying the value by its corresponding weight and dividing the sum of the products by the sum of their weights.
• They have to be supplemented by other measures of description, such as measures of variability which indicate the extent to which values in a distribution are spread around the central tendency