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Hawkins: Biomeasurement 2e

Online Glossary

[#] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Y] [Z]

#

95% confidence limits
the range around a sample mean with very good chance of including the population mean

Σ (sigma)
sum of

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C

confounding variable
a variable that covaries with an independent variable

continuous variable
a variable with infinite number of possible values

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D

degrees of freedom
an adjusted sample size used in calculating various statistics eg., n - 1 (more on this later)

dependent variable
a variable that depends on the independent variable

descriptive statistics
statistics that describe data

discrete variable
a variable consisting of separate indivisible categories

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E

error bar
a T shaped line indicating variability of data on graphs

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F

frequency distribution
the number of individuals/items in each category or interval (graph or table)

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H

histogram
a frequency distribution graph of continuous data

(research) hypothesis
an educated guess to a research question

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I

independent variable
a variable that causes changes in a dependent variable

inferential statistics
statistics that allow us to draw inferences about populations from samples

interquartile range
the difference between the 1 st & 3 rd quartiles (a measure of variability & an e.g., of a descriptive statistic)

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M

mean
an average (a measure of central tendency and an example of a descriptive statistic)

median
the middle value (a measure of central tendency and an example of a descriptive statistic)

mode
the most frequent value (a measure of central tendency and an example of a descriptive statistic)

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N

nominal data
categorical data

normal distribution
a very common and important symmetrical frequency distribution of continuous data

null hypothesis
used in statistical tests of predictions

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O

ordinal data
ranked data

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P

parameter
a value which describes a population

population
an entire set of individuals/items of relevance to a research question

population size (N)
the number of individuals/items in a population

prediction
a statement of what pattern in data is expected if a research hypothesis is true

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R

random sampling
selecting individuals from a population without bias

range
the difference between highest and lowest value (a measure of variability & an example of a descriptive statistic)

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S

sample
a subset of data from a population

sample size (n)
the number of individuals/items in a sample

sampling distribution
a frequency distribution of a statistic e.g., mean

sampling error
the discrepancy between a statistic and a population

scale data
ranked data with scale

standard deviation (σ or s)
the square root of the variance (a measure of variability & an example of a descriptive statistic)

standard error of the mean
the standard deviation of the sampling distribution of means

standardized normal distribution
a normal distribution whose mean has been shifted to zero & x axis marked in units of standard deviation (z scores)

statistic
a value which describes a sample

sum of squares
the sum of squared deviations

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T

t
a statistic that should be used instead of z when the population standard deviation is being estimated from a sample

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V

variance (σ2 or s2)
the mean squared deviation (a measure of variability & an example of a descriptive statistic). Note: for a sample this is the sum of squares divided by the degrees of freedom

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Z

z scores
a standardized measure of the distance of a score from the mean (see also standard normal distribution)

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