Clinical Research Methods
Primary data
This is original data that is collected first hand by the researcher. It can be obtained through experiments, questionnaires, observations.
Rosenhan collected primary data when he went into psychiatric hospitals in his study Sane in Insane places and recorded his experience and the number of days he was admitted.
Strengths
Can be considered reliable as the person conducting the research knows the procedure that was followed and how data was collected. This means they are able to replicate it.
More up to date, making it reliable to the research aim
Higher validity as variables are operationalized so that it represents what the researcher wants to study
Weaknesses
It is expensive and time consuming as data needs to be collected from scratch – this includes finding participants that make a large enough sample to draw conclusions from.
Researchers may be subjective and look for data that fits their hypothesis
Data may be specific to only that time, place and group of pp’s – secondary data may be more generalizable if similar findings are found in more than one area
Secondary data
Data that has been collected by someone else and that is then used for further research e.g. census data might inform researchers about the number of people who live alone. A meta-analysis uses secondary data as it pools together data on one particular topic. Secondary data may be collected before research takes place to find out what is already known about a research area before any further research is carried out
Strengths
Less time consuming and cheaper to use as the data has already been collected – this means more information can be used than what an individual might collect themselves
Secondary data may be the only data available e.g. historical documents and research that it would be unacceptable to conduct
You can check secondary data for validity and reliability by using multiple sources
Weaknesses
May not be valid as the data may not be specific to the research aim, so not looking at what the researcher intends
May be out of date as it may have been collected historically, this means it may not be relevant to the research aim at the time
May be unreliable as the researcher may not know how the data was collected and if it followed a standardised procedure or how the variables were operationalized
Research Methods used to study Schizophrenia
Twin Studies
Monozygotic twins share 100% of the same genes whereas dizygotic twins share 50%. To study genetic effects of schizophrenia the concordance rate of twins can be studied. Concordance is the likelihood of both twins having schizophrenia. If schizophrenia is due to genetic factors there should be a higher concordance rate for MZ twins. Twins can be identified to study through hospital records and then assessing the co-twin – this can be done through personality tests and interviews. Twins can be tested for zygosity (whether they are MZ or DZ) using visual appearance, finger prints and blood tests
Strengths
Using MZ twins is the easiest way to see whether genes affect schizophrenia and provide evidence that behaviour is inherited rather than being environmental
Researchers can identify trends in families and then isolate specific genes associated with schizophrenia
Weaknesses
MZ twins do have some differences that exist even in the womb
Even if schizophrenia is found in both, studies usually find differences e.g. symptoms, onset and outcome
Does not separate cause and effect – may be the environment which both twins are likely to experience
A good sample size is difficult to obtain, especially if trying to find twins raised apart in order to separate nature and nurture
Gottesman and Shields Twin Study of Schizophrenia
For this study, see core studies section
Animal Studies
Animal studies can be used to study biological effects of schizophrenia, and can be used when it is not appropriate to use humans. This is done using lab experiments as the environment is controlled and effects generalised to humans. By altering dopamine levels the researcher can monitor the behaviour of the animal to see if psychotic symptoms occur. This could be through injecting dopamine into rats. Drug treatments can also be tested on animals and effects can be studied e.g. whether reducing dopamine levels reduces psychotic symptoms. Also, damaging parts of the brain, through lesioning, which may be permanent or temporary can help to understand which parts of the brain are involved in schizophrenia e.g. dopamine pathway areas, frontal lobe
Strengths
Animals have genetic similarities to humans and the findings can be generalised.
Using animals is more practical as they have faster life spans and can be controlled more easily than human pp’s
+/- Researchers must follow the guidelines for use of animals in research and conduct a cost-benefit analysis
Weaknesses
However animals are not identical and the findings might not apply to humans which may be more complex.
Using animals in a lab setting may not replicate how schizophrenia develops naturally, and may not be generalised to humans. Also by using animals in a lab reduces the validity.
Castner’s Animal Study for Schizophrenia
Aim:To investigate the effects of pre-natal brain damage using exposure to radiation, to see whether it develops schizophrenic-like behaviour and to explore why schizophrenic symptoms do not seem to appear until puberty
Procedure: Laboratory experiment using two groups of monkeys: half experienced radiation at 70-80 days gestation, the others at 33-40 days (8 monkeys in total) using X-rays at either a high dose (three to six times with 100 Rads) or low dose of radiation (four times with 50 Rads)
Irradiated monkeys were compared with an age matched control group and tested on cognitive tests such as matching, selecting, spatial tasks and visual discrimination at 6-18 months of age (pre-puberty) and again after puberty (3-7 years of age)
Findings: normal development up until adolescence (puberty) and no significant difference between experimental and control groups
Following puberty, irradiated monkeys developed hallucinations and difficulties on memory and problem-solving tests.
Monkeys suffering brain damage between 70 and 80 days of fetal development showed more pronounced abnormalities than monkeys irradiated between 33 and 40 days of gestation
Conclusion: Foetal brain damage predisposes an individual to become schizophrenic after the hormonal changes of puberty.
Evaluation
Generalisability: animal study so while similarities between humans and animals exist, these are not 100% and therefore findings may be different for humans
Reliability: Standardised procedure was used over the exposure to radiation the monkeys were given and a control group was used for comparison
Validity: Lab study which lacks ecological validity and does not measure how psychotic symptoms would occur naturally
Ethics: guidelines of use of animals were followed – only 8 monkeys were harmed in this experiment and the information is beneficial in understanding schizophrenia
Primary data
This is original data that is collected first hand by the researcher. It can be obtained through experiments, questionnaires, observations.
Rosenhan collected primary data when he went into psychiatric hospitals in his study Sane in Insane places and recorded his experience and the number of days he was admitted.
Strengths
Can be considered reliable as the person conducting the research knows the procedure that was followed and how data was collected. This means they are able to replicate it.
More up to date, making it reliable to the research aim
Higher validity as variables are operationalized so that it represents what the researcher wants to study
Weaknesses
It is expensive and time consuming as data needs to be collected from scratch – this includes finding participants that make a large enough sample to draw conclusions from.
Researchers may be subjective and look for data that fits their hypothesis
Data may be specific to only that time, place and group of pp’s – secondary data may be more generalizable if similar findings are found in more than one area
Secondary data
Data that has been collected by someone else and that is then used for further research e.g. census data might inform researchers about the number of people who live alone. A meta-analysis uses secondary data as it pools together data on one particular topic. Secondary data may be collected before research takes place to find out what is already known about a research area before any further research is carried out
Strengths
Less time consuming and cheaper to use as the data has already been collected – this means more information can be used than what an individual might collect themselves
Secondary data may be the only data available e.g. historical documents and research that it would be unacceptable to conduct
You can check secondary data for validity and reliability by using multiple sources
Weaknesses
May not be valid as the data may not be specific to the research aim, so not looking at what the researcher intends
May be out of date as it may have been collected historically, this means it may not be relevant to the research aim at the time
May be unreliable as the researcher may not know how the data was collected and if it followed a standardised procedure or how the variables were operationalized
Research Methods used to study Schizophrenia
Twin Studies
Monozygotic twins share 100% of the same genes whereas dizygotic twins share 50%. To study genetic effects of schizophrenia the concordance rate of twins can be studied. Concordance is the likelihood of both twins having schizophrenia. If schizophrenia is due to genetic factors there should be a higher concordance rate for MZ twins. Twins can be identified to study through hospital records and then assessing the co-twin – this can be done through personality tests and interviews. Twins can be tested for zygosity (whether they are MZ or DZ) using visual appearance, finger prints and blood tests
Strengths
Using MZ twins is the easiest way to see whether genes affect schizophrenia and provide evidence that behaviour is inherited rather than being environmental
Researchers can identify trends in families and then isolate specific genes associated with schizophrenia
Weaknesses
MZ twins do have some differences that exist even in the womb
Even if schizophrenia is found in both, studies usually find differences e.g. symptoms, onset and outcome
Does not separate cause and effect – may be the environment which both twins are likely to experience
A good sample size is difficult to obtain, especially if trying to find twins raised apart in order to separate nature and nurture
Gottesman and Shields Twin Study of Schizophrenia
For this study, see core studies section
Animal Studies
Animal studies can be used to study biological effects of schizophrenia, and can be used when it is not appropriate to use humans. This is done using lab experiments as the environment is controlled and effects generalised to humans. By altering dopamine levels the researcher can monitor the behaviour of the animal to see if psychotic symptoms occur. This could be through injecting dopamine into rats. Drug treatments can also be tested on animals and effects can be studied e.g. whether reducing dopamine levels reduces psychotic symptoms. Also, damaging parts of the brain, through lesioning, which may be permanent or temporary can help to understand which parts of the brain are involved in schizophrenia e.g. dopamine pathway areas, frontal lobe
Strengths
Animals have genetic similarities to humans and the findings can be generalised.
Using animals is more practical as they have faster life spans and can be controlled more easily than human pp’s
+/- Researchers must follow the guidelines for use of animals in research and conduct a cost-benefit analysis
Weaknesses
However animals are not identical and the findings might not apply to humans which may be more complex.
Using animals in a lab setting may not replicate how schizophrenia develops naturally, and may not be generalised to humans. Also by using animals in a lab reduces the validity.
Castner’s Animal Study for Schizophrenia
Aim:To investigate the effects of pre-natal brain damage using exposure to radiation, to see whether it develops schizophrenic-like behaviour and to explore why schizophrenic symptoms do not seem to appear until puberty
Procedure: Laboratory experiment using two groups of monkeys: half experienced radiation at 70-80 days gestation, the others at 33-40 days (8 monkeys in total) using X-rays at either a high dose (three to six times with 100 Rads) or low dose of radiation (four times with 50 Rads)
Irradiated monkeys were compared with an age matched control group and tested on cognitive tests such as matching, selecting, spatial tasks and visual discrimination at 6-18 months of age (pre-puberty) and again after puberty (3-7 years of age)
Findings: normal development up until adolescence (puberty) and no significant difference between experimental and control groups
Following puberty, irradiated monkeys developed hallucinations and difficulties on memory and problem-solving tests.
Monkeys suffering brain damage between 70 and 80 days of fetal development showed more pronounced abnormalities than monkeys irradiated between 33 and 40 days of gestation
Conclusion: Foetal brain damage predisposes an individual to become schizophrenic after the hormonal changes of puberty.
Evaluation
Generalisability: animal study so while similarities between humans and animals exist, these are not 100% and therefore findings may be different for humans
Reliability: Standardised procedure was used over the exposure to radiation the monkeys were given and a control group was used for comparison
Validity: Lab study which lacks ecological validity and does not measure how psychotic symptoms would occur naturally
Ethics: guidelines of use of animals were followed – only 8 monkeys were harmed in this experiment and the information is beneficial in understanding schizophrenia