Instrument error is incorrect or inaccurate error due to a malfunctioning piece of equipment. For example, you’re measuring reaction time but your recording device is faulty, leading to misleading data. Such equipment should be checked and double-checked!
What is a dependent variable?
A dependent variable is the thing that researchers are measuring in an experimental design, their outcome or target variable. For example, if I want to research the effect of facial symmetry on facial attractiveness, then attractiveness is my DV, the thing I’m trying to measure. I would manipulate faces in photoshop and get people to rate their attractiveness on a scale of one to ten, perhaps.
It is called the dependent variable because it is not free to vary by itself, or so we hypothesise. We expect that variation in the DV is dependent on variation in another variable, which we call the independent variable or IV. We manipulate (vary) the IV in order to see if this results in variation in the DV too. If it does, we have found a cause-effect relationship
What is an independent variable?
An independant variable in an experimental research design is one that is manipulated by the investigator. They manipulate this variable while holding others constant, to see if this has any effect on another variable, called the dependent variable. This helps them to learn about cause-effect relationships.
It is called “independent” because, ideally this variable is free to vary by itself, without depending on another variable in order to change. For instance, if I study the effect of male height on attractiveness, and male height is my independent variable, I’m assuming that changes in attractiveness do not cause changes in height. Obviously, this suggestion is quite silly, but only because we already know the answer! When studying new, unknown and abstract variables we don’t know this.
What are the disadvantages of qualitative research?
Some of the disadvantages of qualitative research include:
- It is more difficult to determine the validity and reliability of linguistic data
- It is harder to determine the extent of influence that the researcher had over the results (e.g., through researcher bias). That is, there is more subjectivity involved in analysing the data.
- Note, this doesn’t mean the data is necessarily less valid or reliable, just that it’s harder to know this (with quantitative data, you can do validity test, confirmatory analyses, and other stuff).
- “Data overload” – open-ended questions can sometimes create lots of data, which can take along time to analyse!
- Transcription of recorded interviews can often take a lot of time and/or money
What are the disadvantages of self-report measures?
Some of the disadvantages of self-report measures are as follows:
- People may lie or skew their answers to make themselves look better. For example, people tend to report higher happiness scores when the researcher is of the opposite sex!
- The person may not be able to give an accurate response due to cognitive biases, poor memory, etc.
- People may not have as much self-knowledge as the researchers assume (for example, psychoanalysts would argue that many feelings and much information is unconscious and protected by defence mechanism)
- Technically, they measure a perceptions of a construct rather than measuring it directly, and researchers must assume that this perception is an accurate enough reflection of the ‘real’ thing to be useful
What are the advantages of self-report measures?
Some advantages of self-report measures include:
- You get the respondents views directly
- A good way to measure a participants perception of the thing you are measuring
- Sometimes it only makes sense to measure something by asking the participant about it (opinions, for instance)
- Observational and objective data are not always possible to obtain – for example, life-history studies
- They are quick and simple to administer in many cases (e.g., questionnaires), no complicated technology is required
What is the difference between qualitative and quantitative research?
In basic terms, the difference is that qualitative research collects data in the form of language, and quantitative research collects data in the form of numbers.
For example, “How satisfied are you with your life on a scale of one to ten?” is quantitative.
And “How satisfied are you with your life?” is qualitative.
Qualitative data does not necessarily have to involve asking participants questions and recording the response – it could be a literature search, review of diary entries – anything that is linguistic in format.
What are the advantages of qualitative research?
Some of the advantages of qualitative research are as follows:
- It enables more complex aspects of a persons experience to be studied
- Fewer restriction or assumptions are placed on the data to be collected. For example, if I measure depression by asking ten 1-7 scale questions, I can only collect data on these ten things I’m asking about
- Not everything can be quantified, or quantified easily, and an advantage of qualitative research is that it can investigate these things (for example, individual experiences)
- Individuals can be studied in more depth
- Because fewer assumptions are placed on the thing being studied it is great for exploratory research and hypothesis generation
- The participants are able to provide data in their own words and in their own way
What is a nomothetic measure?
Unlike an ideothetic measure, a nomothetic measure compares individuals against each other. Most tests and measurements fall in this group. For example, if you and I take an IQ test, we can compare our scores and see who is highest, or if we both run 100m we’ll know who is fastest.
What is an ideographic measurement?
An ideographic measurement measures something in an individual without making a comparison to other people. For instance in an IQ test, my IQ score can be compared to other people. If I’m 110 and the person next to me is 140, we know who is higher in this variable. With an ideographic measurement, such as a Q-sort or repertory grip, no comparison is made. For instance, imagine there’s a list of words representing different areas of life; love, work, money, recreation, family – and the task is to place them in order of how much we agree with them, to see what importance we place on different things. We couldn’t say who was ‘highest’ – there’s nothing to be highest in.
