MATH 2.0

Variable - a numerical characteristic or attribute associated with the population being studied. They are further classified as categorical or qualitative and numerical or quantitative.

Nominal data - classifies elements into two or more categories or classes, the numbers indicating that the elements are different but not according to order or magnitude

Ordinal data -a scale that ranks individual in terms of the degree to which they possess a characteristic of interest

Interval data - in addition to ordering scores from high to low, it also establishes a uniform unit in the scale so that any equal distance between two scores is of equal magnitude. There is no absolute zero in this scale.

Ratio data - in addition to being an interval scale, it also has an absolute zero.

Central tendency - also allows the comparison of one data set to another, as well as one piece of data to the entire data set. For example, you could easily draw comparisons between the girls' and boys' heights by calculating the average height for each sample group.

Mean - is the sum of all the values in the observation or a dataset divided by the total number of observations. This is also known as the arithmetic average.

Mean absolute deviation - is the average of how much the data values differ from the mean.

Median (physical middle point) - considered as the physical middle point in a distribution because it is located at the center position when the values are arranged in ascending or descending order, which in turn divides the distribution in half (there are 50% of observations on either side of the median value).

Mode - can be found for both numerical and categorical (non-numerical) data. It is the most commonly occurring value in a distribution. There can be more than one mode for the same distribution of data, (bi-modal, or multi-modal), thus limiting the ability of the mode in describing the center of the distribution. 

Measures of variation - is used to describe the distribution of the data. 

RANGE - is the simplest measure of variation to find.

Standard deviation - is used to quantify the amount of variation or dispersion of a set of data values and represented by the Greek letter sigma o or the Latin letter s. A low standard deviation is an indicator that the data points tend to be close to the mean while a higher value indicates a widerspread from the mean.

Quantiles - It is a score distribution where the scores are divided into different equal parts. 

Quartile - A measure of position that divides the ordered observations or score distribution into 4 equal parts.

Decile - A measure of position that divides the ordered observations or score distribution into 10 equal parts.

Percentiles - A measure of position that divides the ordered observations or score distribution into 100 equal parts.

Pearson Product - The most familiar sort of statistical tool in quantifying the linear relationship between two random variables, x and y.