# Shared Flashcard Set

## Details

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

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
Definition
 A way of thinking
Term
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=nThesumof:(Xi-Xwithalineoverit)2quaredi=n
Term
 Variance formula =
Definition
 i=ns2=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
 IndependanceHomogenity 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 skewsquare 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 isP(A or B) =
Definition
 The sum of A and BP(A) + P(B)
Term
 The sum of the probability of A happening and not happening is
Definition
 1P(A) + P(NotA) = 1
Term
 If the two events are independent, the probability of A and B is
Definition
 The product of the two probabilitiesP(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 treatmentsKruskal-wallis for more than twoWilcoxon for pairedNormal - t-test, paired or not, ANOVA or two way ANOVA
Term
 Continuous data tests of trends
Definition
 Normal - Spearmans rankNon normal - Pearsons or regression
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