# Stats & Mech A level Interactive Glossary

minus the large data set, i've got other ones for that.

population
whole set of items of interest
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cencus
an observation or measure of every member of a population
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sample
a selection of observations taken form a subset of the population which is used to find out info about the population as a whole
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sampling units
the individual units of a population
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sampling frame
a list/collection of all the sampling units
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simple random sample
a sample in which each sampling unit in the sampling frame has an equal chance of being selected
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systematic smapling
the sampling element is chosen at regular intervals from an ordered list
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stratified sampling
sampling in which the population is divided into mutually exclusive strata and a random sample is taken in each strata
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quota sampling
an interviewer selects a sample which reflects the strata of the whole population
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opportunity sampling / convenience sampling
taking a sample from the people available at the time and location of the study and fit the criteria looked for
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quantitate data
data with numerical observations
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qualitative data
data with non-numerical observations
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continuous data
a variable that can take any value
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discrete data
data that can only take specific values
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midpoint of a grouped frequency table
the average of the class boundaries
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the class width of a grouped frequency table
the difference between the upper and the lower boundary
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a measure of location
a single value which describes a position in the data set
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measure of central tendency
a measure of location which describes the centre of the data
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lower quartile
the 25% percentile
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upper quartile
the 75% percentile
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interpolation
estimating the mean, quartiles and percentiles inside a known data range.
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evenly distributed data
(what is assumed when interpolating) :(
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a measure of how spread out the data is (IQR and range)
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IQR (inter-quartile range)
Q3 - Q1
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range
highest value - lowest value
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inter-percentile range
the difference between two different percentiles
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varience
a measure used to display the spread of the data (also it's standard dev squared)
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standard deviation
the square root of varience
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coding
a method of simplifying statistical calculations. each value is coded to make a new set, the coded measures of spread were then un-coded to get the real values.
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outlier
an extreme value that lies outside the overall pattern of the data( anything between Q1 - IQR & Q3 + IQR
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cleaning the data
removal of the anomalies from the data
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box plot
a diagram representing the Q1, Q2, Q3, min, max and any outliers
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cumulative frequency diagram
a diagram used to estimate medians, quartiles and percentages in continuous data
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histograms
a chart for grouped continuous data
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frequency density
frequency / class width
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frequency polygon
the chart made when the tops of the histogram are joined by lines.
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bivariate data
data which has pairs of values for two variables
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independent/explanatory variable
usually plotted on the x-axis, this variable is the variable being measured.
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dependent/response variable
usually plotted on the y-axis, this variable is the variable being measured
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correlation
a description of the nature of the linear relationship in the bivariate data
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least squares regression line (called the regression line)
one type of line of best fit, minimises the sum of the squares of the distances from the line to the points
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extrapolation
predicting outside the given range of data. (less reliable)
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experiment
repeated process that gives rise to a number of outcomes
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event
a collection of one or more outcomes
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sample space
a set of all possible outcomes
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impossible events
events with 0 probability of occuring
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certain events
events with a 1 probability of occurring
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venn diagram
diagram to show the events graphically
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the rectangle in Venn diagrams
the sample space S
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intersection of venn diagram
both events happen
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union of A and B
either A or B or both A & B
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compliment
everything but just A (shown as A')
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mutually exclusive
events that have no outcomes in common (no overlap on the venn). meaning P(A or B) = P(A) + P(B)
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independant events
the probability of one happening is independant of the other happening. Meaning P(A and B) = P(A) x P(B)
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tree diagram
a representation of the outcomes of two or more events happening in succession
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random variable
variable who's value depends on the outcome of a random event
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the probability distribution
full description of the probability of any outcome in the sample space
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probability mass function
P(X=x) = 1/6
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discrete uniform distribution
all the probabilities are the same
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binomial distribution
distribution of success within a set number of trials and a fixed probability of success X~B(n,p)
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index (binomial)
n, the number of trials
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parameter (binomial)
p, the probability
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cumulative probability function
the sum of all the induvigual probabilities up to and including a number of success ect. (basically the cdf function)
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population parameter
the parameter being tested (eg. p in binomial)
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test statistic
the result/conclusion of the test on the sample of the population
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null hypothesis
H0, the hypothesis that you assume is correct
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alternative hypothesis
H1, tells you about the parameter being tested if your assumption is shown to be wrong
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one tailed tests
hypothesis tests with alternative hypothesis in the form p> and p<
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two tailed tests
hypothesis testing with alternative hypothesis in the form p is not equal to
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significance level
a given threshold in which the null hypothesis can be rejected
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critical regions
a region where the probability distribution which if the test statistic falls in it, causes you to reject the null hypothesis
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critical value
the first value to fall inside the critical region
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actual significance level
the probability of incorrectly rejecting the null hypothesis
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p-value
probability
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particle
dimensions of this object are negligible, mass in concentrated at a single point, rotational forces and air resistance can be ignored
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rod
all dimensions but more are negligible, mass in concentrated along the line, no thickness, rigid (no bending or buckling)
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lamina
object with area but negligible thickness, mass is distributed across the surface
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uniform body
mass is concentrated at the centre of mass at the geometrical centre of the object
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light object
mass is negligible - treat as zero mass, tension the same at both ends of string
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Inextensible string
no stretch under load, acceleration is the same in objects connected by a taut inextensible string
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smooth surface
no friction between the surface and object on it
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rough surface
objects in contact with the surface experience a frictional force if they are moving
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wire
rigid thin wire which is treated as one dimensional
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smooth and light pulley
pulley has no mass and tension is the same on either side of the pulley
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particle with a hole in it to thread wire/thread, moves freely along the string, tension is the same on both sides of the bead
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peg
a support from which a body can be suspended or rested
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air resistance
resistance experienced by an object moving through air
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gravity
force of attraction between all things, earth's gravity is uniform and acts vertically downwards
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g
acceleration due to gravity g=9.8m/s/s
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SI units
The international system of units has its base SI units: Mass(kg); length(m); time(s) ect.
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derived SI units
such as acceleration's unit m/s/s
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weight
a force which acts downwards from an object and is caused by gravity
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normal reaction
the force which acts perpendicular to the surface caused by contact with the surface
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friction
a force which opposes the motion between two rough surfaces
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tensions
a force produced when an object is pulled on by a string
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thrust/compression
force acting on an object caused by pushing or combustion.
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bouyancy
the upward force of a body that allows it to float or rise when submerged/floating
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air resistance
a force opposing motion caused by air molecules
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constant acceleration formula/ suvat/ kinematics formula
5 formula that calculate u,v,a,s,t when one or more is missing
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time of flight
the time from the projection (throw) to it hitting the ground
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initial speed
is also called speed of projection (u)
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Newton's 1st law
An object at rest will remain at rest and an object with constant velocity will continue that motion unless an external force acts on the system, making it unbalanced.
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resultant force
a force which causes an object to accelerate in the same direction as the resultant force
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Newton's 2nd law / the equation of motion
forces needed to accelerate a particle is equal to product of mass and acceleration of the particle
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Newton's 3rd law
for every action there is an equal and opposite reaction
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P(A U B) = P(A) + P(B) -P(A and B)
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the multiplication formula for conditional probability
P(A and B)= P(B I A) x P(A)
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normal distribution
a continuous probability distribution, symmetrical (mean=median=mode), total area under curve =1, points of inflection at u+o and u-o
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inverse normal distribution
given a probability, the value of a can be found
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standard normal distribution
a normal distribution with mean 0 and standard deviation 1
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approximation of a binomial distribution using normal
when n is large and p is close to 0.5, using u=np and o=sqrt(np(1-p)
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continuity correction
since binomial is discrete and normal is contionus, the bounds of the probabilities are rounded up/down 0.5.
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moment
a force (Nm) that causes a turning effect on a rigid body (force x distance from pivot)
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coplanar forces
forces that act on the same plane
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resultant moment
the sum of the moments acting on a body
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equlibrium
an object with zero resultant force, therefore with a resultant moment of 0Nm
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centre of mass
the point from which the mass measured
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the point of tilting
when the reaction at any other support is 0
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resolving a force
finding the vertical and horizontal components of a force (all relative)
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the component of a force
the amount of that force acting in a specific direction
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triangle of forces
when the forces are in-equilibrium ,they can be formed into a triangle with the angles preserved
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inclined planes
planes at an angle (forces should be resolved)
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maximum/limiting value (friction)
the magnitude of force needs to overcome friction forces and allow movement (F (force needed) = u(coefficeint of friction) x R (normal reaction)
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coefficient of friction
a measure of roughness
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model of horizontal velocity
when it has a constant velocity (s=vt)
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angle of projection
the angle above the horizontal at which the object is thrown
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range (mechanics)
the distance along the horizontal plane the projectile travels
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greatest height of projectile
achieved when the vertical component of its velocity is equal to 0
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equation of trajectory
a quadratic equation which shows the parabolic nature of the motion
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the limiting equation
when an object is just about to move, it is the maximum amount of frictional force.
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reaction at the hinge
the force exerted on the rod by the wall
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dot notation
short hand for differentiation with respect to time
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## Other cards in this set

### Card 2

#### Front

an observation or measure of every member of a population

cencus

### Card 3

#### Front

a selection of observations taken form a subset of the population which is used to find out info about the population as a whole

#### Back ### Card 4

#### Front

the individual units of a population

#### Back ### Card 5

#### Front

a list/collection of all the sampling units

#### Back 