part one Flashcards
what are the two types of variability
- intrinsic (natural system)
2. extrinsic (measurement error)
when do you define the population
population must be defined before the sampling proess has begun as it will dictate how you sample
how are frequency curves characterised
by 2 key parameters: location (eg middle, mean, mode) and dispersion (spread, variance)
why are the parameters of the frequency curve important
we can never know the true population parameters therefore we can infer from sampling
what is mu (μ)
population mean
what is x
sample mean
what is σ
population standard deviation
what is s
sample standard deviation
what is SEM
standard error of mean measure variabilty of the sample mean
what are the 6 main steps of the logical framework ?
- observations
- models
- hypothesis
- null hypothesis
- experiment and sampling
- interpretation and results
what is the next step after you retain the null
you refute model and hypothesis. therefore you go back to observations and find out what was missing
what is the next step after you reject the null
you retain model and hypothesis. you dont stop. you ask why is this the case ie what are the mechanisms that make this model true?
what are the 2 types of observations
- casual (personally seen in nature with no prior knowledge
2. previously quantified in literature
what types of phrases must be used when making casual observations
it appears, it seems, it looks like
ie not certain
what is a model
the reason behind observations used to explain process
how do you state model from a casual observation
it is correct because it happens in nature in this location where i saw it
how do you state a model from a quanitifed observation
literature behind process eg this is because…
what is a hypothesis
what you predict if the model is true.
use the structure… if I do this then i will observe this/i will expect this
what is the difference between mensurative and manipulative
mensurative experiments are observational, they do not change the experiment.
manipulative experiments change system to understand patterns (you need literature first)
what is the point of a null hypothesis and what is this approach called
falsificationist approach. the hypothesis can never been proved because the population cant be measured. therefore you test everything outside of the population and what remains is true.
limited by its design, a mensurative study can only give certain interpretations. what are they
correlative not causational
it doesnt let you understand cause and effect or mechanisims. merely descriptive/qualittative
what is required for appropriate manipulative studies
appropriate controls and adeuqate prior biological knowlegde of the system
what is the difference between precision and accuracy
precision is the measure of spread, (precise = narrow, imprecise = wide) you can test using standard error of mean
accuracy is the measure of how close the sample mean is to the population mean (usually you cannot test accuracy
SEM
s/sqrt n