The main types of variables:
Independent variable- what the researcher establishes or actively manipulates. May also be called a "factor".
Example. Therapy symptoms of schizophrenia.
Dependent variable- what is measured.
Example. Therapy symptoms schizophrenia.
The simplest experiment is one independent variable with two levels.
NP levels
NP has several meanings (levels). Level - the value or aspect of NP. The number of NP levels is not limited.
Example: types of therapy (psychoanalysis, rational psychotherapy, etc.)
Number of independent variables.
There can be only one or several NPs in an experiment. A simple experiment - 1 NP. Factor - more than 1 NP.
Example: influence psychotherapy And drug treatment for symptoms of schizophrenia. Each of the NPs can be represented by several levels:
Therapy - psychoanalysis, rational therapy, etc.
Drug treatment - Haldol, Thorazine, etc.
Independent variable
Varieties of NP:job characteristics(easy, hard, etc.) features of the situation (external conditions), controlled features (states) of the subject; (anxiety)
If the constant characteristics of the subject (subjective variables), for example, personal anxiety, gender, intelligence, act as an analogue of NP, it is correct to call the study not an experiment, but a correlation study.
Studies with Subjective and Controlled Variables
|
Variables |
Name |
Groups |
External variables |
conclusions |
|
Controlled Variables |
Experiment (true) |
Equivalent - differences only in NP levels |
controlled |
About the causes of behavior |
|
Subjective variables |
Correlation study |
Non-equivalent - differences in other parameters (VP) |
Not controlled |
About differences between groups. Impossible about the causes of behavior |
Dependent variable
ZP - registered parameters of behavior (a value that is measured in the experiment).
Types of POs: accuracy (number of errors), latent time (from the moment a signal is presented to the choice of an answer), duration, or speed, of execution,
pace, or frequency, of actions, productivity, categories of behaviors
Levels of measurement and RFP
Any measurement can be assigned to one of 4 types (levels):
Nominal- classification of objects according to qualitative features, for example, party affiliation.
LDPR - 1, ER - 2, PZh - 3, Communist Party of the Russian Federation - 4, EPRST - 5
When comparing, one can talk about belonging to one or different parties, but one cannot conclude that one of the compared has a greater party affiliation than the other.
Ordinal- ranking order according to the degree of manifestation of any feature: good very good best washing machine
You can say that someone (something) is better than another, but you cannot say how much better. Often used in preference research.
interval- the order is established in accordance with the degree of manifestation of the attribute and the magnitude of the difference between the objects of measurement in terms of the variable being evaluated is determined.
Example, temperature scale Celsius
We can say that something (someone) is more (better) than another and how much more (better).
A distinctive feature - there is no "absolute" zero. The most common level of measurement in psychological research (standardized scales such as the Intelligence Scale).
Relationship level- the order is established in accordance with the degree of severity and the magnitude of the difference between the objects of measurement in terms of the variable being evaluated is determined and there is an absolute zero mark on the scale (absolute zero).
Examples: weight, height, task completion time.
It is possible to say which of the objects of measurement is larger, how much, how many times the given thing (property) exists or not.
_____________________________________________________________________________
Characteristics of the RFP: reliability, validity, sensitivity
Reliability- accuracy of measurement, stability of results in time.
Example. Results of several measurements (testing) of the same object
(20 points "true" value)
Reliable tool 19 20 20 19 18 19
Unreliable tool 18 11 23 29 20 15
One way to assess reliability is to retest the same group of subjects with an interval of 2-3 weeks, followed by calculation of the measure of connection (correlation coefficient) - retest reliability.
Validity - information about What measures our test (or whether we measure what we want to measure). For example, the optimism test - whether it actually measures optimism. One way to assess validity is to correlate test scores with expert scores or test scores of known validity.
sensitivity- sensitivity of the dependent variable to changes in the independent.
Low sensitivity: when NP is manipulated, the RFP does not change, although in reality a pattern (relationship between variables) exists.
Varieties of dependencies between NP and RFP:
No dependency
Monotonically increasing dependence
Monotonically decreasing dependence
Nonlinear dependence U- figurative type
Inverted U- figurative dependence
Complex quasi-periodic dependence
Rice. Monotonically increasing dependence
Signs of a causal relationship between two phenomena:
1. Precedence in time of cause to effect.
2. The presence of a statistical relationship between two variables (cause and effect).
3. Other (alternative) explanations of the relationships A and B are excluded. To do this, external variables must be controlled.
External variables - basic methods of control (according to Druzhinin)
elimination of external variables; exclusion of the presence of an external variable.
constancy of conditions; the influence of the external variable remains unchanged on all subjects
balancing- use of the control group. To isolate the effect of an external variable, more than one CG is used.
counterbalancing- the order of presentation of different tasks, stimuli, influences in one of the groups is compensated by a different order of presentation of tasks in the other group. Used when it is possible to obtain order or sequence effects - previous conditions change the effect of subsequent conditions. When using counterbalancing, the effect of the sequence is purposefully distributed to all experimental conditions.
randomization- random selection and distribution of subjects. Allows you to exclude the influence of the individual characteristics of the subjects on the result of the experiment.
Validity of the experiment
Validity - the quality of the experiment, which guarantees the validity of the conclusions:
that it is the experimental factor that is the cause of the changes recorded in the dependent variable (internal validity);
that the revealed dependence is natural, it can be extended to certain out-of-experimental situations (external validity).
Internal validity– the degree of correspondence between the real experiment and the ideal one.
The Perfect Experiment: NP - changes, RF - is fixed, other conditions remain unchanged (equivalence of the subjects, no changes, the ability to conduct experiments indefinitely, etc.
Threats to internal validity(Campbell D.T. Models of experiments in social psychology and applied research. M., 1980.)
History (background)- events that occur during the experiment along with the influence of the experimental factor,
natural development(changes in subjects that are not associated with specific events, but are a consequence of the passage of time (for example, increased hunger or fatigue, etc.);
Test effects- the influence of tasks previously completed by the subjects on the results of the repeated test (the effect of the "first measurement", experience of participation in other experiments and tests);
Error, measurement tool instability- malfunction of technical means, instability of the level of attention of observers, changes in their physical and mental state;
Statistical regression- a consequence of the selection of groups on the basis of extreme indicators;
Selection of subjects- non-equivalence of the experimental and control groups in terms of composition;
Elimination during the experiment- uneven dropout of subjects from the experimental and control groups before the experiment ends;
Interaction between selection and natural development, which can be taken as the effect of the experimental factor.
An example of research and evaluation of threats to internal validity: the effectiveness of the program to reduce exam anxiety in students. The level of anxiety in a group of students before and after the program is compared.
Possible threats:
History (background)- changing the rating system to reduce anxiety
natural development– adaptation to learning conditions and reduction of anxiety
Tools– replacing the test with another test or improving the skills to use the test
Testing- a change in attitude towards one's qualities as a result of obtaining information about them (in the general case - addiction or increased susceptibility)
regression to the mean- "improvement" of indicators in the group formed from participants with low anxiety scores
External validity - a measure of the conformity of the experimental procedure with reality. An experiment that completely reproduces external reality is called full compliance experiment. External Validity Determines Possibilities generalization(generalizations) of sample data for the entire population.
Generalization
to other populations(age, social status, gender, ethnic characteristics, etc.)
74% of all research is done on students. Students are distinguished by higher abilities, they are more selfish and susceptible to social influences, it is easier to change their attitude to various issues.
The external validity of Lawrence Kohlberg's study of the moral development of children is called into question, because. the subjects are only teenage boys.
for other conditions(the dilemma "artificial laboratory conditions - ordinary conditions")
Ulrich Neisser initiated a movement to study phenomena outside of laboratories to ensure environmental validity.
to another time context(historical, political, etc. background)
Solomon Asch explored conformity in the 1950s. Conclusion: College students are susceptible to pressure from above. Historical context of the study: the supremacy of conservatives in politics and society, the Cold War; conformity, obedience are values significant for the survival of society. If the study is repeated in our time, will a similar result be obtained?
External Validity Threats:
Pre-testing- a possible change or increase in the susceptibility of subjects to experimental exposure under the influence of preliminary testing (the reactions of persons who have undergone preliminary testing will not be representative of those who have not been subjected to this);
Interaction effects of subject selection and experimental factor- the registered effect is characteristic only for this group, does not appear in other parts of the studied population;
The conditions for organizing an experiment that cause a reaction to the experiment - fixed reactions are caused not only by the experimental factor, but by the knowledge that an experiment is underway (therefore, it is incorrect to extend the data obtained to persons exposed to the experimental factor in non-experimental conditions);
Mutual interference of experimental influences, which often occurs when the same subjects are subjected to several influences, since the influence of earlier influences, as a rule, does not disappear.
In order to find out its effect on the dependent variable.
Dependent variable- in a scientific experiment, a measured variable, changes in which are associated with changes in the independent variable.
The independent variable, for example, in a psychological experiment, can be considered the intensity of the stimulus, and the dependent variable is the ability of the subject to feel this stimulus.
Types of relationship between variables
- The dependent variable is not sensitive to changes in the independent variable.
- Monotonically increasing dependence: an increase in the values of the independent variable corresponds to a change in the dependent variable.
- Monotonically decreasing dependence: an increase in the values of the independent variable corresponds to a decrease in the level of the independent variable.
- Non-linear dependence of the U-shaped type - found in most experiments in which features of the mental regulation of behavior are highlighted
- Inverted U-shaped dependence - obtained in numerous experiments and correlation studies.
- Complex quasi-periodic dependence of the level of the dependent variable on the level of the independent.
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See what "Dependent variable" is in other dictionaries:
DEPENDENT VARIABLE- (eng. dependent variable) variable, which is influenced by another factor in the experiment (independent variable). See Lab Experiment... Great Psychological Encyclopedia
See DEPENDENT VARIABLE. Antinazi. Encyclopedia of Sociology, 2009 ... Encyclopedia of Sociology
DEPENDENT VARIABLE, see VARIABLE ... Scientific and technical encyclopedic dictionary
- (dependent variable) The variable on the left side of the regression equation, the change in which is correlated with changes in the causal variables, i.e., the variables on the right side of the equation. For example, in a linear regression equation yi = α+βxi+γzi+εi where i =… … Economic dictionary
Dependent variable- - see Function ... Economic and Mathematical Dictionary
dependent variable- — [Ya.N. Luginsky, M.S. Fezi Zhilinskaya, Yu.S. Kabirov. English Russian Dictionary of Electrical Engineering and Power Engineering, Moscow, 1999] Electrical engineering topics, basic concepts EN dependent variable ... Technical Translator's Handbook
dependent variable- priklausomasis kintamasis statusas T sritis fizika atitikmenys: engl. dependent variable vok. abhängige Veränderliche, f rus. dependent variable, fpranc. variable dependante, f … Fizikos terminų žodynas
DEPENDENT VARIABLE- - a variable that changes under the influence of an independent variable and takes on different values. For example, if the nature of formal relationships in a dyad of employees of an organization acts as an independent variable ... ... Encyclopedic Dictionary of Psychology and Pedagogy
dependent variable- A variable whose variability we seek to explain by the influence of one or more independent variables. The distinction between dependent and independent variables usually rests on substantive considerations. Synonyms: criterion variable, ... ... Dictionary of Sociological Statistics
Dependent variable- - a variable that changes under the influence of another (independent) variable ... Social Work Dictionary
Independent variable (NP)- an influencing factor that is the cause of change.
The independent variable (book definition) - experimental influence or experimental factor - is controllable, i.e. a variable actively changed by the researcher, in other words, a functionally controlled variable; presented at two or more levels. In the experimental hypothesis is understood as a causal factor.
Dependent variable (CV)- what we consider as the effect of the influence of the independent variable.
Dependent variable (book definition) is a “response”, or a variable measured in an experiment, changes in which are causally determined by the action of an independent variable (IP). In a psychological study, it is represented by the performance of the subject, any form of assessment of his subjective judgments and reports, psychophysiological parameters, etc.
side variable - is any factor, perceived or actual, that can affect the dependent variable. There can be many such factors, the task of the experimenter is to control the impact of these factors.
It is important to note that in any experiment we are interested in the causal - investigative connection. Establishing the fact in the study is not sufficient, you need to establish the cause and method of verification.
9. External ( they are side) variables. Ways to control variables.
External or additional variables(DP) is a concomitant stimulation of the subject that affects his response. The set of DP consists, as a rule, of two groups: external conditions of experience and internal factors. Accordingly, they are usually called external and internal DP. TO external DP include the physical environment of the experiment (illumination, temperature, sound background, spatial characteristics of the room), parameters of apparatus and equipment (design of measuring instruments, operating noise, etc.), time parameters of the experiment (start time, duration, etc.), personality of the experimenter. TO internal DP include the mood and motivation of the subjects, their attitude towards the experimenter and experiments, their psychological attitudes, inclinations, knowledge, skills, skills and experience in this type of activity, the level of fatigue, well-being, etc.
Ideally, the researcher seeks to reduce all additional variables to nothing, or at least to a minimum, in order to highlight the “pure” relationship between the independent and dependent variables. There are several main ways to control the influence of external DP: 1) elimination of external influences; 2) constancy of conditions; 3) balancing; 4) counterbalancing.
1) The elimination of external influences consists in the complete exclusion from the external environment of any external DP.
2) Creation of constant conditions. The essence of this method is to make the effects of DP constant and the same for all subjects throughout the experiment.
3) In cases where it is not possible to create and maintain constant conditions throughout the experiment, resort to the method of balancing. This method is used, for example, in a situation where the external DP cannot be identified. In this case, balancing will consist in using the control group. The study of the control and experimental groups is carried out under the same conditions, with the only difference that in the control group there is no effect of the independent variable.
4) Counterbalancing as a way to control external DP is most often practiced when the experiment includes several series. The subject finds himself in different conditions sequentially, however, previous conditions may change the effect of subsequent ones. To eliminate the “sequence effect” that arises in this case, experimental conditions are presented to different groups of subjects in a different order.
Types of experimental plans.
It is customary to single out the following main experimental designs: designs with one independent variable, with two independent variables, and factorial designs.
Plans with one independent variable:
The design of this experiment should have the following features:
1) using one of the strategies for creating equivalent groups, most often - randomization;
2) the presence of an experimental and at least one control group;
3) completion of the experiment by testing and comparing the behavior of the group that received the experimental treatment (X1) with the group that did not receive the treatment (X0).
If it is necessary to use more than 1 level of exposure, then plans with several experimental groups (according to the number of exposure levels) and one control group are used.
The use of a 2-group randomized design with post-exposure testing controls for the main sources of intrinsic invalidity (as defined by Campbell). The plan allows you to control the influence of the composition of groups, spontaneous dropout, the influence of the background and natural development, the interaction of the composition of the group with other factors.
Plan for two randomized groups with preliminary and final testing. This plan is widely used in social and clinical experiments (for example, the Stanford Prison Experiment).
In the study of mental processes, such a plan, as a rule, is not used, since preliminary testing affects the internal validity of the experiment by setting certain settings.
Factor experiments are used when it is necessary to test complex hypotheses about the relationships between variables. The general form of such a hypothesis is: “If A1, A2, .... A, then B.” Such hypotheses are called complex, combined, etc. At the same time, there can be various relationships between independent variables: conjunctions, disjunctions, linear independence, additive or multiplicative, etc. Factor experiments are a special case of a multidimensional study, during which they try to establish relationships between several independent variables. and several dependent variables. In a factorial experiment, as a rule, two types of hypotheses are tested simultaneously:
1) hypotheses about the separate influence of each of the independent variables;
2) hypotheses about the interaction of variables, namely, how the presence of one of the independent variables affects the effect on the other.
The factorial experiment is built according to the factorial plan. Factorial design of the experiment is to ensure that all levels of independent variables are combined with each other. The number of experimental groups, as a rule, is equal to the number of combinations of levels of all independent variables.
Independent variables - these are the means that are available to the experimenter to influence the subjects.
Dependent variable - these are the changes that occur in the state, behavior, communication and activities of the subjects under the influence of the experimenter.
External variables (noise) - those factors (conditions) that also affect the subjects in addition to the will of the experimenter (fatigue, noise outside the window).
The experimenter should strive to reduce the impact of external variables on the subjects.
Independent variables
Quality - are expressed in the fact that any effect is either present in the experiment or absent.
(For example: experimenter's prompt (maybe, maybe not)).
quantitative - is expressed in various degrees (more than two) of the influence of the experimenter on the subjects.
Independent variables may take the following forms:
Show up in:
In job elements;
In the elements of the experimental situation;
In the characteristics of the state of the subject.
In the task, the experimenter varies:
1. Characteristics of impact (strong, weak impact).
2. The material of the task (written, on the computer).
3. The type of response of the subject (verbal and non-verbal).
4. Evaluation scale (money).
5. Instruction (may change, but should not).
6. The purpose and action of the subject.
7. Means that the subject has.
8. Obstacles that are placed on him.
9. The system of rewards and punishments for the subjects.
In the situation, they will:
1. Physical parameters:
How long;
Times of Day.
Equipment location;
The appearance of the premises;
illumination;
Sounds and noises;
temperature;
Placement of furniture;
Experiment behavior time
2. Socio-psychological parameters:
Work in the presence of the experimenter;
Either work in isolation;
In Group;
Or when communicating with the experimenter.
3. Features of the state of the subject:
Mental stress;
The level of experienced stress, fear, frustration: the level of conformity;
Rivalry, etc.
Types of dependent variables
(what the experimenter manipulates)
One-dimensional – only one parameter is registered. It is he who is considered a manifestation of the dependent variable. (Reaction time)
Multidimensional - a number of parameters are selected that are fixed. (For example: problem solving time, solution quality, originality, etc.).
Fundamental .
Dependent variable is considered as a function of individual parameters of its manifestation. (For example: aggressiveness level – is considered as a function of the interaction of the following parameters:
verbal aggression;
non-verbal aggression;
Indirect aggression (loudly slammed the door);
The manifestation of irritability, etc.
, Where A
- parameter.
According to this principle, the level of aggression is determined. Questionnaire for the definition of aggressiveness.
The change in the dependent variable is determined by the change in the parameters of the subject's behavior. They are conventionally divided into formal dynamic And meaningful .
TO formal dynamic include:
Task accuracy
Latency (i.e. latent time from the moment the signal is presented to the choice of the answer).
Execution time
Pace or frequency of action
Productivity – i.e. the ratio of the result obtained to the execution time.
extrapunity – external accusatory behavior (S. Rosenzweig)
intropunity - self-blame.
Immunity – no one blames, but tries to understand the situation.
Dependent variable must be valid (degree of conformity), reliable And sensitive.
Validity – the degree of compliance of the dependent variable with the hypothesis.
Dependent Variable Reliability - means that the level of manifestation of the dependent variable is steadily fixed during the experiment.
Sensitivity - talks about how much the dependent variable changes when the independent variable changes.
There are 2 variants of manifestation of the type of insensitivity of the dependent variable:
ceiling effect - manifests itself in the fact that the task is so simple that the level of its performance by the subject is higher than all levels of the independent variable. (For example: multiplication table).
floor effect - on the contrary, it occurs when the simplest level of the independent variable is so difficult for the subject that he is not able to perform it.
Dependent Variable Changes manifested in a change in the state of a person, communication, behavior, activity, facial expressions, posture, activity, emotionality, etc.
A variable is something that can be changed, such as a certain characteristic or value within a study. In psychology, variables are used to determine whether changes in one factor lead to changes in another.
Dependent and independent variables
In experimental psychology, there are two types of variables:
- Independent variable is a factor controlled by the authors of the study. For example, in an experiment investigating the impact of sleep deprivation on performance, sleep deprivation is the independent variable.
- Dependent variable- a phenomenon that experimenters fix and measure. In our example, the performance test results are just the dependent variable.
Extraneous and distorting factors
It is important to note that independent and dependent variables are not the only variables present in experiments. In some cases, extraneous factors can have a noticeable effect on the relationship between the independent and dependent variable (and therefore on the results of the experiment). For example, in our example, such factors include the age and gender of the subjects.
There are two main kinds of extraneous variables:
- subject variables. These are extraneous variables associated with the individual characteristics of each of the participants, which can affect how they react to the conditions of the experiment. These may include gender and age characteristics, origin, mood, anxiety, intelligence, awareness, etc.
- situational variables. These are extraneous variables associated with environmental phenomena that can affect the response of the participants. For example, if a participant is tested in a cool room, the cold temperature is considered an extraneous variable. Some participants may not respond to coolness, some may be distracted and annoyed.
In most cases, extraneous variables are also controlled within the experiment: the researchers themselves can select participants according to certain criteria or set other conditions.
Definition of variables
Before conducting an experiment, it is important to give the operating parameters of the variables - scientists determine the independent and dependent variables, decide in what framework they should be kept and how they will be measured.
For example, in our experiment on the effect of lack of sleep on performance, we must create working definitions for variables. If our hypothesis sounds like “students who experience lack of sleep will perform worse on tests,” then, first, we need to decide who we mean by “students.” Next, we need to define the "lack of sleep" variable. In our example, this would be, say, less than five hours of sleep the night before the test. And finally, we must decide on the "test". Let this be a little theory test...
