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BE428 Lecture 2: Producing Data
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- 1What is data?Consists of information coming from observations, counts, measurements or responses
- 2What is the definition of data?pieces of information about individuals organised into variables
- 3what is the definition of an individual?a particular person, object, cell, molecule ect
- 4what is the definition of a variable?a particular characteristic of an individual
for example: size, weight, density - 5what is the definition of a dataset?a set of data identified with particular circumstances
- 6what is statistics?the science of collecting, organising, analysing and interpreting data to make decisions
- 7why is statistical analysis used?to make inferences about a population by studying a relatively small sample chosen from it
- 8what is a parameter?a number that describes a population characteristic
for example: average age of all people in the US - 9what is a statistic?a number that describes a sample characteristic
for example: average age of people from a sample of three states - 10what are the two branches of statistics?descriptive
inferential - 11what is involved in descriptive statistics?organising, summarising and displaying data
for example: tables, charts, averages - 12what is involved in inferential statisticsusing sample data to draw conclusions about a population
- 13what are the two types of data?qualitative/categorical
quantitative - 14what is qualitative/categorical data?consists of attributes, labels or non-numerical entries
for example: blood group, eye colour, smoker - 15what is quantitative data?numerical measurements
for example: weight, temperature, cell count - 16what are the two types of quantitative variable?discrete
continuous - 17what is a discrete variable?can only take certain values from a finite set
- 18what is a continuous variable?can take any value
- 19what are the four levels of measurement?nominal
ordinal
interval
ratio - 20what is the definition of the nominal level of measurement?qualitative data only
categorised using names, labels or quantities
no mathematical computations can be made
for example: gender, eye colour, blood type - 21what is the definition of the ordinal level of measurement?qualitative or quantitative data
data can be arranged/ranked in order
differences between data entries are not meaningful
for example: positions in a race, survey answers - 22what is the definition of the interval level of measurement?quantitative data
data can be ordered
differences between data entries is meaningful and can be measured
zero represents a position on a scale (zero does not imply none)
interval scales tell us about the order and the exact value between units
for example: celsius temperature scale - 23what is the definition of the ratio level of measurement?similar to interval level
zero entry is an inherent zero (implies none)
a ratio of two data values can be formed
one data value can be expressed as a multiple of another
ratio scales tell us about the order, the exact value between units and they have an absolute zero
for example: height and weight - 24what are the steps in designing a statistical study?1. identify the variable(s) of interest (the focus) and the population of the study
2. develop a detailed plan for collecting data using a representative sample of the population
3. collect the data
4. describe the data using descriptive statistics techniques
5. interpret the data and make decisions about the population using inferential statistics
6. identify any possible errors - 25what are the four methods of data collection?observational study
experiment
simulation
survey - 26what is the definition of an observational study in terms of data collection?a researcher observes and measures characteristics of interest of part of a population
- 27what is the definition of an experiment in the terms of data collection?a treatment is applied to part of a population and responses are observed
- 28what is the definition of a simulation in terms of data collection?uses a mathematical or physical model to reproduce the conditions of a situation or process
often involves the use of computers and specialist software - 29what is the definition of a survey in terms of data collection?an investigation of one or more characteristics of a population
commonly done by interview, mail or telephone - 30why is a control used?to remove the effect of all other factors apart from the one being investigated
an assumption is made that everything apart from the manipulation is the same in the two groups so any differences must be a result of the manipulation - 31what are the four types of control?experimental control
statistical control
temporal control
placebo control - 32what is an experimental control?used to remove all possible effects on the observations other than that of the experimental manipulation itself
- 33what are the two types of experimental control?negative control
positive control - 34what is a negative control?a control group that is not exposed to the experimental treatment or to any other treatment that is expected to have an effect
- 35what is a positive control?a control group that is not exposed to the experimental treatment but that is exposed to some other treatment that is known to produce the expected effect
- 36what is a statistical control?alternative to experimental control
rather than fixing all possible factors that can affect the observations, the factors are measured and incorporated into the analysis - 37what is a temporal control?worth incorporating if investigating the effect of a long-term manipulation
uses one control group and one test group with the manipulation starting after monitoring has been underway for some time
ideally will use half of the time before and half of the time after the manipulation - 38what is a placebo control?an inactive substance is given to one group of participants while the treatment being tested is given to another group
results obtained in the two groups compared to see if treatment is more effective than placebo - 39what is the placebo effect?a subject reacts favourably to a placebo when they have been given no medical treatment
- 40what two methods of placebo control are used to prevent the placebo effect?blinding
double-blind - 41what is blinding?a technique where the subject does not know whether they are receiving a treatment or a placebo
- 42what is a double-blind experiment?neither the subject nor the experimenter knows if the subject is receiving a treatment or placebo
- 43what is a confounding variable?happens when the experimenter cannot tell the difference between the effects of different factors on a variable
- 44what is the definition of replication?the repetition of an experiment using a large group of subjects
- 45what is the definition of randomisation?the process of randomly assigning subjects to different treatment groups
- 46what are the three methods of randomisation?completely randomised design
matched pairs design
randomised block design - 47what is the definition of completely randomised design?subjects are assigned to different treatment groups through random selection
- 48what is the definition of matched pairs design?subjects are paired according to similarity
one subject in the pair is randomly selected to receive one treatment while the other subject receives a different treatment/control - 49what is the definition of randomised block design?divide subjects with similar characteristics into blocks, and then randomly assign subjects to treatment groups within each block
- 50what are the four sampling techniques?simple random
stratified
cluster
systematic - 51what is the definition of a simple random sample?every possible sample of the same size has the same chance of being selected
- 52what is the definition of a stratified sample?divide population into groups and select a random sample from each group
- 53what is the definition of a cluster sample?divide the population into groups and select all of the members in one or more (but not all) of the clusters
- 54what is the definition of a systematic sample?choose a starting value at random then choose every nth member of the population
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- 4 BE428 Fichas sobre BE428 Lecture 2: Producing Data, creado por Caitlin M el 19/09/2018.
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