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Experimental Design and Analysis
Biologically centered
82
Other
Undergraduate 1
01/11/2016

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Term
`Induction
Definition
The derivation of general ideas from specific observations - not used by scientists
Term
Hypothetico-deductive reasoning
Definition
Observations lead to plausible hypotheses, which we then attempt to falsify, if we cannot prove them false, they are good hypotheses, but not necessarily right
Term
Theory
Definition
A general set of ideas or rules used to explain a group of observations
Term
Paradigm
Definition
A way of thinking
Term
Paradigm shift
Definition
A change in the way we think about a subject
Term
Null Hypothesis
Definition
H0, The form of a hypothesis that we formally test, it predicts nothing will happen
Term
Alternative hypothesis
Definition
A specific prediction about an experiment
Term
Nominal data
Definition
Data in categories with names
Term
Discrete data
Definition
Data that always rises in integers
Term
Ordinal data
Definition
Non-quantitative ranked data, normally used in questionnaires
Term
Continuous data
Definition
Quantitative measurements on a continuous scale
Term
Descriptive statistics
Definition
Measures calculated from a data set which summarise some characteristics of the data
Term
Measures of central tendancy
Definition
Mean, median and mode
Term
Frequency histogram
Definition
A graph showing the total number of quantitative observations in each of a series of numerically ordered categories
Term
Distribution
Definition
Shape of a data set
Term
Sum of squares
Definition
Total of all the squared deviates in a data set, squaring removes the minus, SS shows the magnitude of the variability but not the direction
Term
Variance
Definition
s2- the average size of the squared deviates in a sample - an estimate of the population variance
Term
Standard deviation
Definition
s - the average size of deviates in a data set.
Term
Population
Definition
All individuals in a group
Term
Sample
Definition
A sub-set of a population, meant to represent it
Term
Normal distribution
Definition
Bell-shaped, Gaussian, 68.5 of all data points are in one SD
Term
Standard error of the mean
Definition
A measure of the confidence we have in our sample mean as an estimate of the real mean
Term
Skew
Definition
If skewed to the right, there is a long tail to the right, atc. for left
Term
Parametric tests
Definition
Tests which make many assumptions
Term
Non-parametric tests
Definition
Tests which make fewer assumptions
Term
Poisson distribution
Definition
A distribution where a maximum possible count is far above the mean, resulting in a skew
Term
Binomial distribution
Definition
A distribution where the maximum count is close to the mean
Term
Bar chart
Definition
Used for visualising differences
Term
Scatter graph
Definition
Used for visualising trends
Term
Measurement precision
Definition
A measurement is not precise ifthere is an unbiased measurement error
Term
Measurement accuracy
Definition
A measurement is accurate if it is free from bias, bias occurs when there is a systematic error in your measurements
Term
Confounding effects
Definition
A confounding effect is something that influences your results in a way that can be confused with the effect you are studying
Term
Floor effect
Definition
Effects of a variable are only visible once above a certain point
Term
Ceiling effect
Definition
Effects of a variable are only visible below a certain point
Term
Independent samples t-test
Definition
A statistical test designed to test for a difference between the means of two samples of continuous data
Term
Type I error
Definition
The rejection of the null hypothesis when it is true
Term
Type II error
Definition
The failure to reject the null hypothesis when it is false
Term
Pseudoreplication
Definition
the use of non-independant data points as if the were independant
Term
Paired design
Definition
A test designed were samples are not independant of each other, normally used to examine change
Term
Homogeneity of variance
Definition
If the variance is homogenous, it is the same in each sample
Term
Chi squared
Definition
A test which is used to examine differences between observed and expected counts
Term
Pearsons correlation coefficient
Definition
The statistic used to test the significance of correlations between two variables. Can only be used with linear relationships and normal distributions
Term
Spearmans rank correlation coefficient
Definition
Non-parametric correlation test
Term
ANOVA
Definition
Tests the null hypothesis that the samples means are not different
Term
Kruskal-Wallis test:
Definition
Non-parametric one way ANOVA
Term
ANCOVA
Definition
Combines anova and regression
Term
Hypotheses should be
Definition
Clear, Precise, Plausible, Able to produce testable predictions
Term
X with a line over it=
Definition
mean
Term
X=
Definition
data point
Term
Xi=
Definition
All data point
Term
SS formula =
Definition
i=n
Thesumof:(Xi-Xwithalineoverit)2quared
i=n
Term
Variance formula =
Definition
i=n
s2=thesumof(xiXwithalineoverit)2quared
i=1
_____________________________________
n-1
Term
SD =
Definition
Square root of variance
Term
95% of samples are within
Definition
1.96 SDs
Term
Standard error of mean formula
Definition
SEM = s
___
squareroot n
Term
Which tests have more statistical power?
Definition
Parametric tests
Term
For t tests, df=
Definition
n1+n2-2
Term
Parametric test standard assumptions
Definition
Independance
Homogenity of variance
Term
Alternative t test if the variances are not the same
Definition
Welch test
Term
To test if the variances are the same?
Definition
Levenes test
Term
If data is not normal, you can transform it by...
Definition
Squaring all the points, eliminating a right skew
square root arcsine all the points, eliminating a left skew
Term
Alternative T-test if the data is not normal
Definition
two-sample wilcoxon test
Term
Post hoc tests
Definition
adjust for chance of a type 1 error
Term
In regression, we analyse
Definition
the affect of a variable on another variable
Term
If events A and B are mutually inclusive, the probability of event A or B is
P(A or B) =
Definition
The sum of A and B
P(A) + P(B)
Term
The sum of the probability of A happening and not happening is
Definition
1
P(A) + P(NotA) = 1
Term
If the two events are independent, the probability of A and B is
Definition
The product of the two probabilities
P(A and B) = P(A).P(B)
Term
Binomial probability distribution
Definition
n! x p^i x (1-p)^n-i
--------------------------
i! x (n - i)!
Where the probability of the first outcome is p, the number of events i, and the amount of trials n
Term
As the binomial distribution gets bigger, we expect to see
Definition
A skew to the left
Term
Poisson distribution
Definition
m^i e^-m
_-------- = P(i)
i!
Term
Factorial
Definition
Put ! after a number means x all numbers up to that, e.g. 3! is 1x2x3
Term
The binomial probability distribution can be used to
Definition
figure out the probability of a certain size deviation from an expectation
Term
To convert non-normal data to ordinal
Definition
rank it
Term
0! =
Definition
1
Term
e =
Definition
the sum of an infinite series
Term
Logarithim
Definition
the number by which ten has to be raised before it is equal to x
Term
To compare two means
Definition
Z = (x1 - x2) / √(((s1^2)/n1)+(s2^2)/n2))
where z is the test statistic, n1 is the first sample size and n2 is the second, x1 is the first mean and x2 is the second, and s1 is the first standard deviation and s2 is the second
Term
To convert non-normal data to normal
Definition
convert it to base10log
Term
Tests For nominal data
Definition
binomial, poisson, chi squared
Term
Normallity tests
Definition
Kolmogorov-Smirnov, less powerful, more general, or shapiro-wilk
Term
Continuous data tests of difference
Definition
Not normal - Mann-whitney for two treatments
Kruskal-wallis for more than two
Wilcoxon for paired
Normal - t-test, paired or not, ANOVA or two way ANOVA
Term
Continuous data tests of trends
Definition
Normal - Spearmans rank
Non normal - Pearsons or regression
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