Statistical Terms
categorical variable - a variable for which each value falls into one of a set of
groups (e.g. gender, political party, plant species, type of behavior)
confidence level - the probability, expressed as a percentage, that a confidence
interval encloses the population parameter (We can be 95% confident that this interval
encloses the actual population parameter.)
continuous variable - a variable that can assume values corresponding to any of the
points contained in one or more intervals (e.g. height, weight, time)
correlation - a relationship between 2 variables
dependent or response variable - a variable of interest to be measured in an experiment,
we usually are interested in determining the effect of one or more independent variables
on the response variable
independent variable - a predictor variable, one which is not being affected by other
variables in the experiment (e.g. in a food choice study, the type of food would
be the independent variable and the amount eaten would be the response variable)
mean - the sum of the measurements divided by the number of measurement contained
in the data set (average)
median - the middle number when the measurements are arranged in ascending or descending
order
normal distribution - a bell-shaped probability distribution
null hypothesis - 1(statistics) the hypothesis that is being falsified by a specified
statistical test (usually that the values being tested are equal)
random sample - elements selected from a population such that every set of n elements
in the population has an equal probability of being selected
range - the largest measurement minus the smallest measurement
standard deviation - the square root of the variance
statistic - a number calculated from a sample of observed data to make an inference
about the population to which the sample belongs
statistically significant - implies that you have used statistical methods, which
account for means and variances, to conclude that your measurements for different
populations or treatments are different
statistics - the science of data – collecting, classifying, summarizing, organizing,
analyzing, and interpreting numerical information
variance - the sum of the squared distances from the mean divided by (n
– 1)2 (ecology)
the predicted outcome based on the assumption that the resulting pattern is what
would occur in the absence of the hypothesized ecological proccess (essentially,
a prediction of ‘no difference’)