Research Methods (AS & A2) Flashcards
What is accuracy?
Measure of how close recorded result is to real value
What is precision?
Intervals between possible recorded results, eg ruler measuring in millimetres → more precise than one in centimetres
What is a representative sample?
Sample accurately reflecting complete data set
What does a reliable method provide?
Consistent, accurate results
What is an anomalous result and how can you see whether it’s a ‘real’ result or caused by other variables?
-Result differing from other results w/ which it was expected to be similar
-Repeating the study
What does a valid study provide?
Precise, accurate, reliable results upon which conclusions can be based
What factors required are in environmental fieldwork/lab work?
-Appropriate risk management
-Practical equipment & materials required & how to use these safely + correctly
-Data to be collected & analysed; using appropriate apparatus/instruments to record quantitative measurements (eg pH) & measure abiotic/biotic factors, selecting right sampling & statistical analysis techniques
What are the general principles of scientific investigations?
-Identifying topic of interest
-Finding out what’s already been learnt
-Formulating hypothesis/null hypothesis that can be tested
-Designing & carrying out experiment to test hypothesis
-designing investigation, eg including consideration of location & timing of sampling sites, # & size of samples, standardised technique, stat analysis
-Analysing results & drawing conclusions
-Planning further research to fill gaps in existing knowledge/develop study further
Scientific methodologies; why is careful planning needed?
To ensure data collected can be used to conclude whether a hypothesis should be rejected or accepted
Scientific methodologies; what is done if all the data existing about a particular issue can’t be collected?
-Sub-samples collected, then used to estimate full situation
-Will only produce reliable conclusions if sub-samples are representative
Scientific methodologies; what must the planning of sub-samping consider?
Factors that may affect how representative they are; location, timing, size, number
Scientific methodologies; what should be used to test the reliability of a method?
A preliminary study
Sampling; what needs to be considered for the location of a sample?
-If data aren’t being collected at single location, decisions will need to be made about positioning of sampling sites
-It’s essential to avoid intro of bias due to deliberate selection of locations for convenience/to support or dismiss hypothesis → can be achieved by random/systematic sampling
Sampling; how does the shape of the study area affect random sampling?
-If study area has regular shape, grid can be laid out & coordinates of sampling sites selected w/ random numbers
-If study area has irregular shape, all possible sampling sites can be numbered + selected using random number generator
Sampling; what is systematic sampling and how is choice of sampling site made?
-Involves samples taken using chosen interval distance/spacing
-Choice of sampling sites isn’t based on choices made using observable differences in study area
Sampling; how should the distance between sampling sites be chosen?
To detect variable data w/out collecting more data than necessary → can be determined w/ preliminary study
Sampling; why does sampling need to sometimes be done on different occasions and how is the timing determined?
-If factor measured changes w/ time, it’ll be necessary to sample on diff occasions to produce mean result representing ‘typical’ value/identify trends in changing values
-Ideal time interval betw samples depends upon rate at which values change → can be determined w/ preliminary study
Sampling; what are some examples of sampling time scales and variables that may be affected?
-Long-term changes; population changes eg tigers, area of rainforest, atmospheric CO² level
-Seasonal changes; presence of migratory species, populations of annual wildflowers, temp, atmospheric CO² level, river level
-Diurnal changes (24hr); light levels, temp, atmospheric CO² levels
-Weather-related changes (minutes-weeks); flying insect activity, wind velocity, temp
-Other short-term changes; road noise level
Sampling; when are different sample sizes needed and how can this be determined?
-If variable measured isn’t homogeneous, larger samples are more likely to produce representative results
-Sample size needed can be determined using preliminary study
Sampling; how and why can the number of samples vary within studies?
-Single samples may not be representative as may be variability betw samples. Collecting multiple will help eliminate effect of variability
-# of samples needed to produce representative mean depends upon degree of scatter around mean, assessed by calculating standard deviation
-Can be found w/ preliminary study
-# of samples collected will also depend upon how results will be analysed. It’s easier to assess degree of stat sig of results w/ larger sample
Sampling; why and how are techniques standardised?
-To allow comparison of results collected at diff times/locations/researches, must be collected in exactly the same way
-Other variables affecting results must either be controlled/monitored to assess their effects
Population studies; why are good surveys essential in ecological monitoring?
-To find out which species are present
-To monitor habitat conditions, how they change & which conditions individual species require
-To monitor features of populations, how they change over time
-Population size
-Age structure
-Growth rates
-Breeding rates
-Territory size
-Population movements
-Reliable, representative data important in making good conservation management decisions
Population studies; what is the technique used to monitor ecological conditions in ecosystems & species there depend upon?
-on what is measured
-Affected by rapid development of new techniques that may produce better results; more representative, quicker, more cost effective
Population studies- ecological techniques; what is a quadrat and what can the results be used for?
-Study area, usually square, within which populations can be studied
-Results from number of quadrats can be scaled up to estimate overall situation for entire area
Population studies- ecological techniques; how should quadrat size be selected and what are examples of typical quadrat sizes?
-Dependent upon the habitat & groups of species being studied
Typical sizes=
-Lichens; 10 x 10cm
-Ground flora; 0.5 x 0.5m
-Trees in forest; 100 x 100m
-Bird presence survey; 10 x 10km
Population studies- ecological techniques; what is an open frame quadrat?
-Mark out a study area
-Smaller ones may be made of metal/plastic frame
-Larger ones use reference coordinates marked out by measuring tapes/GPS coordinates
Population studies- ecological techniques; what is a grid quadrat?
Sub-divided into smaller squares, eg 10 x 10, each small square representing 1% of area
Population studies- ecological techniques; what is a point quadrat and when can it be used?
-Used to collect similar info to other quadrats but don’t use square area
-Can be used where ground flora → too tall for other quadrats as it’d be flattened & provide unrepresentative results; % cover estimate would be inaccurate & shorter plants may be obscured by flattened foliage of taller plants
-Wooden frame supports metal rods, usually 10. Each time rod touches leaf, counts as 10% cover
Population studies- ecological techniques; what are the limitations of quadrats?
-Subjective judgement may be involved; eg estimating % cover
-Quadrat frame may flatten/move plants
Population studies- ecological techniques; what is the method for using a pond net?
-Can be swept through water/aquatic vegetation to capture invertebrates, amphibians, fish
-Using a particular length of sweep/number of sweeps, can be used in an attempt to standardise method & produce comparative data
Population studies- ecological techniques; what is the limitations of pond nets?
Mobile species may escape
Population studies- ecological techniques; what is kick sampling and the method used for it?
-Collects invertebrates living on riverbed
-Net held w/ its straight edge on river bed & its face open to the current
-Riverbed in front of net is disturbed by repeatedly scraping boot over it. Invertebrates that are dislodged are caught in the net
-Controlling number & length of kicks can be used to standardise the method
Population studies- ecological techniques; what are the limitations of kick sampling?
-Accurate standardisation is difficult
-Buried organisms/those fixed on stones may not be dislodged
-Some organisms can swim & avoid net
-Water flow rate → variable, affects capture rate
-Fragile organisms may be destroyed
Population studies- ecological techniques; why are surber samplers mare efficient than kick sampling?
Provide a more standardised technique
Population studies- ecological techniques; what is the method used for kick samplers?
-Fixed area of riverbed is sampled within box-like frame
-Riverbed is disturbed using trowel/similar tool & stones are inspected manually
-Netting at sides of net opening reduces number of organisms escaping
Population studies- ecological techniques; what are the limitations of surber samplers?
-Can only be used where water is fast enough to carry organisms → net
-Sampler’s small size can make it hard to set on rough substrates in deep water resulting in loss of large organisms
Population studies- ecological techniques; what are plankton nets and the method used for them?
-Catch planktonic organisms floating in water, some can be used to give quantitative estimates of populations
-Fine mesh is pulled through water, can be used vertically/horizontally
-Net can be fixed where there’s a current/may be towed through water
-Different mesh sizes are used for diff sizes of organisms. Phytoplankton are smaller than zooplankton so smaller mesh size is used
Population studies- ecological techniques; what are the limitations of plankton rets?
-Nets w/ coarse mesh size don’t catch smaller organisms
-Nets w/ fine mesh may become clogged by phytoplankton, preventing water flawing into net
Population studies- ecological techniques; what are sweep nets and what is the method used for them?
-Are sturdy nets used to sample invertebrates in ground vegetation like grassland
-Net is swept through vegetation so dislodged organisms are caught
-Standardisation of method can be attempted by using same number of sweeps of same length
Population studies- ecological techniques; what is the limitation of sweep nets?
Mobile species may escape, like flying insects
Population studies- ecological techniques; what is the method used for aerial insect nets and its limitations?
-Lightweight nets used to capture flying insets like butterflies
-Successful collection depends on agility of researcher & prey
Population studies- ecological techniques; what is the method used for colonisation media?
Some species can be monitored by providing suitable habitats that they may colonise
Population studies- ecological techniques; what are the limitations of colonisation media?
-Not all species can be monitored as they may not use media
-Accurate population estimates aren’t possible as proportion colonising media isn’t known
Population studies- ecological techniques; what are pitfall traps used for?
Sampling populations of mobile animals on ground surface
Population studies- ecological techniques; what is the method used for pitfall traps?
-Container is placed in a hole in the ground w/ its open end making a close fit w/ soil & top being level w/ the ground surface
-Cover is supported over the opening to exclude predators that may eat animals that are caught & to prevent flooding by rain
-Trap is checked after a standard period of time, eg 24 hrs
-Preservative fluid may be used to kill captured animals for later study
Population studies- ecological techniques; what are the limitations of pitfall traps?
-Only mobile animals that live on the ground surface are caught
-More mobile species are more likely to be caught
-Trapped carnivorous animals may kill other organisms that have been caught
-If a preservative is used, it may attract/repel certain species
-Some species avoid traps/can escape
Population studies- ecological techniques; what are beating traps used for?
To sample invertebrates present on vegetation above ground
Population studies- ecological techniques; what is the method used for beating traps?
-Sheet/tray is placed beneath vegetation which is beaten several times w/ a stick
-Dislodged invertebrates fall onto sheet & are collected for identification & counting
Population studies- ecological techniques; what are the limitations of beating trays?
-It’s difficult to standardise method between researchers, eg vigour of hitting branches
-Some species aren’t dislodged
-Thicker branches shake less so organisms are less likely to be dislodged
-Some species fly away & aren’t caught
-Higher branches can’t be reached
Population studies- ecological techniques; what are light traps used for?
To collect night-flying insects attracted by bright lights, usually UV lights
Population studies- ecological techniques; what is the methods used for light traps?
-Flying insects, esp moths attracted to light fall into a container. Container is checked the following morning
-Insects that have been caught are identified & counted
Population studies- ecological techniques; what are the limitations of light traps?
-Moths only fly during their adult phase & activity is affected by weather + seasons so failure to find species doesn’t mean it’s absent
-Brightness & light wavelengths emitted by light can affect their attractiveness to insects so it may be hard to compare results produced by diff types of trap
Population studies- ecological techniques; what are tüllgren funnels used for?
To sample mobile invertebrates in leaf litter/soil
Population studies- ecological techniques; what is the method used for tüllgren funnels?
-Sample of leaf litter/soil placed on mesh beneath a light
-Light & heat repel some mobile invertebrates which more downwards, pass through mesh & fall into container
-Tüllgren funnel is left operating for standard period of time
-Invertebrates collected are identified & counted
Population studies- ecological techniques; what are the limitations of tüllgren funnels?
-Only species repelled by heat/light will be collected
-Some organisms may die/stop moving due to heating/desiccation before they’re collected
-Some organisms are too large to pass through mesh
Population studies- ecological techniques; what do suction samplers do?
-Capture airborne insects/invertebrates dislodged from vegetation
-Some just show presence of organisms but some give quantitative data
Population studies- ecological techniques; what is the method used for suction samplers?
There’s several types of suction sampler used to collect invertebrates from the ground, vegetation or atmosphere;
-Air suction samplers capture flying insects. If air flow rate is measured & cross-sectional area of collector tube is known then number of insects per unit vol of air can be estimated
-Motor-driven suction samplers can be used to sample invertebrates on ground vegetation. Area of ground covered by suction pipe is known, so population density of invertebrates can be estimated
-Rooter= suction sampler used to pick up invertebrates that have been found. It’s a handling method, not a population sampling technique
Population studies- ecological techniques; what are the limitations of suction samplers?
-Some invertebrates may not be caught by an air sampler; may sense it and fly away
-Some insects may not be dislodged from vegetation by suction sampler
Population studies- ecological techniques; why do earthworms need to be extracted from the soil?
They’re difficult to observe, so need to be removed for their populations to be monitored
Population studies- ecological techniques; what is the method of soil flooding?
-Mark out a sample area of suitable size, 0.5 x 0.5m/1 x 1m
-Remove vegetation that may hide worms at surface
-Add irritant solution, eg detergent/mustard in water
-Keep adding until soil is saturated
-Saturate surrounding area (so worms are less likely to move sideways)
-Add more as solution infiltrates into soil
-Collect worms coming to surface
-Continue collecting until no more worms appear/for suitable time period/standardised time period
-Count/measure/weigh/identify collected worms
Population studies- ecological techniques; what are the limitations of soil flooding?
-Irritant solution may not percolate through impermeable soils
-Irritant solution may not reach deepest worms
-Worms may more sideways/down
-Worms may die
-Worms may move too slowly to be collected during study period
Population studies- ecological techniques; what is the method and limitations of soil pit extraction?
-Method; pit of chosen area & depth is dug, eg 0.5x 0.5 x 0.5m, soil is hand sorted & worms collected
-Limitations; smaller worms may be overlooked, digging may disturb worms that move sideways/down out of sample site
Population studies- quantitative/comparative/numerical measures; how can you measure population size/density?
-Method used depends on features of species studied; for some it may be possible to count all individuals in a pop., eg all birds in a cliff nest colony
-Some species are dispersed over large areas so sub-sampling is necessary
-Some species can’t be easily observed but may be possible to catch sample of pop. Mark-release-recapture may be used to estimate total pop., eg Lincoln Index
Population studies- quantitative/comparative/numerical measures; what are abundance scales and how are they categorised?
Involve allocating species to diff categories based on relative abundance, eg dafor scale species are categorised into the following groups;
-Dominant
-Abundant
-Frequent
-Occasional
-Rare
Population studies- quantitative/comparative/numerical measures; what are the advantages and disadvantages of adundance scales?
-Judgement of abundance is subjective, can vary betw diff people but it’s quick & allows many areas to be studied quickly
-Results aren’t quantitative so statistical analysis of results may not be possible
Population studies- quantitative/comparative/numerical measures; what is species richness/diversity and what does it involve?
-Measure of number of diff species found in area
-Often focuses on particular taxon, eg birds, ground flora, reptiles
-To standardise method & allow for comparison between sites, may be used in specific areas, eg tree species in 100 x 100m squares
Population studies- quantitative/comparative/numerical measures; what is species frequency?
Measure of dispersal of species by recording proportion of all samples in which it was found
Population studies- quantitative/comparative/numerical measures; what is species density?
Relates number of species found to specific area & makes species richness results more compatible, eg number of species per square metre
Population studies- quantitative/comparative/numerical measures; how is percentage vegetation cover estimated?
By observing the proportion of;
-Ground covered by vegetation for ground flora
-Sky obscured by vegetation for tree cover
Grid quadrats are commonly used
Population studies- quantitative/comparative/numerical measures; what does the Lincoln index estimate?
Total population by catching a proportion of the population
Population studies- quantitative/comparative/numerical measures; what is the method used for the Lincoln index?
-Sample of population is caught, counted, marked, released
-Some time later, second sample is caught & counted. Individual already marked from first sample are counted
-Lincoln index formula is used to estimate total population;
Number in 1st sample x number in 2nd sample/number in 2nd sample with marks
Population studies- quantitative/comparative/numerical measures; what are the limitations of the Lincoln Index?
Estimation of population relies on some assumption;
-Individual animals are mobile & can be caught
-Size of population doesn’t change during time of study, eg due to births, deaths, migration
-Being caught & marked doesn’t affect survival rates
-Marks dan’t fall off/wear away during study
-Marked individuals mix freely w/ rest of population
-All individuals in population have same chance of being caught
Population studies- quantitative/comparative/numerical measures; what is Simpson’s Index of Biodiversity used to assess?
-Variety & abundance of species in area
-May be used to consider all species but is often used for single taxonomic group, eg biodiversity of ground flora/insects
Population studies- quantitative/comparative/numerical measures; what is the formula of Simpson’s Index of Biodiversity and what do values indicate?
-D = N (N-1) / sum of (n(n-1) , where;
-D= index of diversity
-N= total number of individuals of all species
-n = number of individuals of a particular species, each species has own n (n-1) value
-Higher value= higher biodiversity
Population studies- quantitative/comparative/numerical measures; what is the method used and limitation of species identification ID keys?
-Often dichotomous keys where sequence of questions narrows down possibilities, based on unique visible features; size, shape, markings
-Limitations; some species lack characteristic features & look the same as other species, characteristic features may not always be present, eg flowers and seeds
Specialist techniques used in ecological research- imagery; why are image databases used?
Individuals of some species can be recognised from image databases of unique features
-Eg Tiger facial stripes, Cheetah tail markings, Whale Shark spot patterns, dolphin fin marks/injuries & zebra stripes
Specialist techniques used in ecological research- imagery; what does being able to identify individuals provide information on?
-Territory size
-Population movements, like migrations
-Lifespans
-Social groupings
Specialist techniques used in ecological research- imagery; what is the limitation of image databases?
Few species have unique features that can be used to identify individual
Specialist techniques used in ecological research- imagery; what are motion-sensitive cameras used for?
Habitat monitoring to detect presence/activity of animals using visible light photography during day or infrared photography at night
Specialist techniques used in ecological research- imagery; what can Closed circuit TV (CCTV) be used for?
To observe animal behaviour w/ lower risk of disturbance than if researchers visit site, eg for researching birds’ nests
Specialist techniques used in ecological research- marking; what is a method used to identify individual animals previously caught?
Rings placed on birds’ legs; provide information on movements & lifespan if are caught later
Specialist techniques used in ecological research- DNA databases; how can DNA be used to detect the presence of a species?
Presence of some aquatic species can be detected from DNA of cells they shed into water; environmental DNA/eDNA
Specialist techniques used in ecological research- DNA databases; what are examples of eDNA being used and how has this been advantageous?
-eDNA evidence of presence of legally protected Great Crested Newt may prevent development being permitted in UK that’d damage its habitat
-In USA, presence of non-indigenous Bighead Carp & Silver Carp is detected using eDNA
Specialist techniques used in ecological research- DNA databases; how can regional populations be identified using DNA and what are examples of this?
-Each separate population within species has its own unique gene pool
-May be possible to identify where plant/animal came from if its DNA can be compared w/ DNA database for diff regional populations
-This technology is being developed to track sources of tropical timber, elephant ivory & some commercially fished species, eg cod & haddock
TBC P405
