Appendix B Flashcards
chi-square test
goodness of fit or contingency test. Test of significance designed to determine if the difference in observed and expected frequencies are significant within a selected degree of probability (frequency data vs continuous data)
continuous variable
infinite number values possible (ex. measurement of haemoglobin in blood may be in whole grams or fractional units)
discrete variable
fixed numerical values with no intermediates possible (ex. number of toes, number of trees, number of white blood cells)
dispersion
scatter of values from a central point
histogram
graph of a frequency distribution of a continuous variable
interpolation
predicts values within range of values measured but which do not actually exist in the set
Mean
denoted by X with line on top
measurement error
reflects discrepancy between a measurement and the true value of the variable being measured
median
middle value in an ordered set of values (half values are less than and half more than)
mode
most frequently occurring value
normal distribution
a theoretical frequency distribution that is bell shaped and symmetrical
population
in stats, all possible values of a particular variable in all sampling units of a particular group
precision
nearness of values of successive measurements of the same specimen
range
largest values - smallest values
scientific notation
write number as factors of powers of 10
significant figures
reflects the accuracy for which we are able to measure
standard deviation
a measure of the dispersion of a set of data about the mean (calculated as the square root of the variance)
- average size of the deviation from the mean
standard error
a measure of how reliable the sample mean is as an approximation to the population mean (standard deviation/square root of sample size)
student’s t-test
a test of significance used to determine if the mean values of two groups of data are significantly different within a selected degree of probability (are populations the same with respect to variable tested). Tests for difference between two sample means.
test of significance
Statistical test designed to evaluate probability of rejecting the null hypothesis when it is true. Example if chance of rejecting null is 1% when it is in fact true, the significance level is 1% for that test.
variability
range of measured values in a population
variance
a measure of how much scatter there is around the mean
- calculated as the sum of the difference between each measurement and the mean divided by the sample size minus one
- average size of the squared deviations from the mean
variation
members of a given population differ from each other by characteristics they possess as a result of both genetic and environmental factors affecting the organism.
single measurement consists of
- unit measured
- scale factor showing relative magnitude of value
- significant figures