Click on an item below to see the definition

###### p value:

Hand-in-hand with the test statistic is the p value which indicates
the probability of getting the characteristics observed in a sample if the null hypothesis were true.

###### Paired t test:

A test on the change that occurs in
a measurement carried out on the same subject under two different conditions,
eg. before and after a therapeutic treatment.

###### Parameters:

Variables not in the data, but in the model (eg. distribution,
line of best fit) which describes it, eg. mean, gradient, standard deviation.

###### Parametric statistics:

That branch of statistics based on the estimation and testing of
parameters (usually normally distributed data).

*See also Non-parametric statistics, Parameters.*

###### Percentile:

A 10 percentile is the value (of a particular variable such as weight)
beneath which 10% of the population falls. A 50 percentile is the value beneath which 50% of the population
falls. These could also be written as 10%ile and 50%ile.

###### Placebo:

A non-active treatment applied as a control in a study where psychological
factors could affect the outcome. This allows the observation and quantification of any procedural effects involved
in the trial that have nothing to do with any administered treatment.

*See also Placebo effect.*

###### Placebo effect:

Improvement in outcome that is consistent but not due to any treatment or
non-treatment administered. This is only a factor for human beings and possibly animals where psychology of care
can affect outcome.

*See also Placebo.*

###### Population:

The set of all possible subjects from which a sample can be drawn.

###### Population distribution:

The distribution of the population from which a sample was drawn.

*See also Distribution.*

###### Power:

The ability to reject the null hypothesis when it is false.

###### Probability:

The likelihood of an event happening;
must be between 0 and 1.

###### Proportion:

An observed fraction of the total.

###### Prospective study:

By nature a long-term experiment, which plots the progression from
an initial state to the particular state under examination. For example, how many first-time prisoners from a
particular prison re-offend within one year of release?

*See also Retrospective study.*

###### Protocol:

The protocol of an experiment is a set of rules laid down at the start
to impose a rigid structure on everyone involved, to ensure consistency, and to provide a focus for the
experiment by defining of the decision rule.

"Being a senior academic teaching research to undergraduate and post graduate health care students,
the inevitable ogre of statistics appears early in the students experience of my courses. There are few,
if any, ways that I have discovered that have my students running for their statistics books with
enthusiasm and glee. Needless to say the common fear of numbers and the often complex explanations
offered to underpin basic statistical understanding tend to elicit an, at best, lukewarm response
and at worst, total denial. However, I have been using Statistics for the Terrified now for the last
few years and for those students that use it it has been a transformation. The interactive nature,
plenty of visual examples and clear and straightforward explanations of the basic concepts behind
probability, data distributions, measures of central tendency and spread and common statistical tests
means, first that they don't have to listen to me droning on, second the independent nature of the
experience increases both life long and deeper learning and lastly provides me with an initial direction
in which to send them when they ask the more simple questions.

"So........they get to be less bored of me, they learn in a deeper and more individual way and I don't
have to spend lots of time reiterating the basics to hundreds of students"

**David Newell**

Research Director, AECC

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