Chemometrics quizzes Flashcards
Difference between nominal and ordinal variable
Nominal is categorical and cant be ranked ordinal is also categorical and a number but can be ranked
Whats the difference between discrete and continuous variables
discrete variables are specific numebrs like integers and continuous can exist between real numbers
Inferential vs descriptive stats?
Inferential stats make an inference based off the data (analyzes it - draws conclusions) - descriptive just describes it (eg mean, median mode)
What does the null hypo mean and what is the alternative hypo
null is that there there is no sig difference between the groups or means -alt is that there is
What is a two tailed t test
a t test that looks for differnce both greater and less than (either direction
Why do we use post hoc tests with ANOVA
to see specifically the relationship between groups - which groups specifically have a statistically significant relation
With bonferroni adjusted p value - what do you use to adjust the p value
of tests/comparisons
In two way anova how many factors do you have
2
When checking for normal dist - is p < or> than 0.05 for normal
p>0.05
know how to name a box and whisker plot
we have the whisker and the interwuartile range
we also have min, max, lower quartile, upper quartile and median
What is a correlation matrix
its a matrix showing correlation between all combinations of variables
what is one way repeated measures ANOVA
When the same subjects are measured more than once (eg same subject but different time points
With correlatoins what does the magnitude of the correlation describe
Strenght of relation
Name 2 ways 1st order poynomial regressions differ from 2nd order
Different DOF, quadratic has C term, quadratic non linear
What is a residual and when they are all summed what do they equal
Distance of each point from best fitted line - all summed up they equal 0
if slope not statiscally significant (p > 0.05) what does this mean - if the overal model has ap value not sig what does this mean
If slope not sig that means no relationship between x and y (b=0)
if model not significant - doesnt effectively predict
What is the difference between two way anova and MANOVA
more than one variable
What is the equation for linear regression
y = mx + b
Things to check on influence plot
Outliers, Leverage poitsn and influence
4 assumptions for linear regression
error in x negligible, dependant vriable needs to be normally dist, variance in error across y should be constant and x and y are continuous and independant
What is the parametric Mann whitney U
2 sample independant t test
What is the non parametric equivalent for the one way anova test
Kruskal Wallis
Difference between supervised and unsupervised learning
Supervised - we know outcome and this informs the model - unsupervised only give data no existing info or input
What are the two things used to calculate PCA scores
Magnitude (concentration) and influence (variance)
