Flashcards
Stats Chapter 1
Cards in this deck (77)
- 1Between-Groups DesignAnother name for independent design
- 2Between-Subjects DesignAnother name for independent design
- 3BimodalA description of a distribution of observations that has two models
- 4Binary VariableA categorical variable that has only two mutually exclusive categories (e.g. being dead of alive)
- 5Boredom EffectRefers to the possibility that performance in tasks may be influenced (the assumption is a negative influence) by boredom or lack of concentration if there are many tasks, or the task goes on for a long period of time.
- 6Categorical VariableThe university you attend is a good example of this: students you attend RDC are not also enrolled at Harvard or UV Amsterdam, therefore, students fall into distinct categories.
- 7Central TendencyA generic term describing the centre of a frequency distribution of observations as measured by the mean, mode, and median.
- 8Concurrent ValidityA form of criterion validity where there is evidence that scores from an instrument corresponds to concurrently recorded external measures conceptually related to the measured construct.
- 9Confounding VariableA variable (that we may or may not have measured) other than the predictor variables in which we're interested that potentially affects an outcome variable.
- 10Content ValidityEvidence that the content of a test corresponds to the content of the construct it was designed to cover.
- 11Continuous VariablesA variable that can be measured to any level of precision ( time is an example because there is no limit on how finely it could be measured).
- 12Correlational ResearchA form of research in which you observe what naturally goes on in the world without directly interfering with it. This term implies that data will be analyzed so as to look at relationships between naturally occurring variables rather than making statements about cause and effect. Compare with cross-sectional research, longitudinal research and experimental research.
- 13CounterbalancingA process of systematically varying the order in which experimental conditions are conducted. In the simplest case of there being two conditions (A and B), counterbalancing simply implies that half of the participants complete condition A followed by condition B, whereas the remainder do condition B followed by condition A. The aim is to remove systematic bias caused by practice effects or boredom effects.
- 14Criterion ValidityEvidence that scores from an instrument correspond with (concurrent validity) or predict (predictive validity) external measures conceptually related to the measured construct.
- 15Cross-Sectional ResearchA form of research in which you observe what naturally goes on in the world without directly interfering with it, by measuring several variables at a single point in time. In psychology, this term usually implies that data come from people at different age points, with different people representing each age point.
- 16Dependent VariableAnother name for outcome variable. This name usually associated with experimental methodology (which is the only time it really makes sense) and is used because it is the variable that is not manipulated by the experimenter and so its value depends on the variables that have been manipulated.
- 17DevianceThe difference between the observed value of that variable predicted by a statistical model.
- 18Discrete VariableA variable that can only take on vervain values (usually whole numbers) on the scale.
- 19Ecological ValidityEvidence that the results of a study, experiment or test can be applied, and allow inferences, to real-world conditions.
- 20Experimental ResearchA form of research in which one or more variables are systematically manipulated to see their effect (alone or in combination) on an outcome variable. This term implies that data will be able to be used to make statements about cause and effect. Compare with cross-sectional research and correlational research.
- 21FalsificationThe act of disproving a hypothesis or theory.
- 22Frequency DistributionA graph plotting values of observations on the horizontal axis, and the frequency with which each value occurs in the data set on the vertical axis (a.k.a. histogram)
- 23HistogramA frequency distribution.
- 24HypothesisA prediction about the state of the world (see experimental hypothesis and null hypothesis).
- 25Independent DesignAn experimental design in which different treatment conditions utilize different organisms (e.g., in psychology, this would mean using different people in different treatment conditions) and so the resulting data are independent (a.k.a. between-groups or between-subjects design).
- 26Independent VariableAnother name for a predictor variable. This name is usually associated with experimental methodology (which is the one time it makes sense) and is used because it is the variable that is manipulated by the experimenter and so its value does not depend on any other variables (just on the experimenter).
- 27Interquartile RangeThe limits within which the middle 50% of an ordered set of observations fall. It is the difference between the value of the upper quartile and the lower quartile.
- 28Interval VariableData measured on a scale along the whole which intervals are equal. For example, people's ratings of this book on amazon.com can range from 1 to 5; for these data to be interval it should be true that the increase in appreciation for this book represented by a change from 3 to 4 along the scale should be the same as the the change in appreciation represented by a change from 1 to 2, or 4 to 5.
- 29JournalIn the context of academia a journal is a collection of articles on a broadly related theme, written by scientists, that report new data, new theoretical ideas or reviews/critiques of existing theories and data.
- 30KurtosisThis measures the degree to which scores cluster in the tails of a frequency distribution.
- 31LeptokurticA distribution with positive kurtosis has too many scores in the tails and is too peaked.
- 32Level of MeasurementThe relationship between what is being measured and the numbers obtained on a scale.
- 33Longitudinal researchA form of research in which you observe what naturally goes on in the world without directly interfering with it by measuring several variables at multiple time points.
- 34Lower QuartileThe value that cuts off the lowest 25% of the data. If the data are ordered and then divided into two halves at the median, then the lower quartile is the median of the lower half of the scores.
- 35MeanA simple statistical model of the centre of a distribution of scores. A hypothetical estimate of the 'typical' score.
- 36Measurement ErrorThe discrepancy between the numbers used to represent the thing that we're measuring and the actual value of the thing we're measuring (ie., the value we would get if we could measure it directly).
- 37MedianThe middle score of a set of ordered observations. When are is an even number of observations the median is the average of the two scores that fall either side of what would be the middle value.
- 38ModeThe most frequently occurring score is a set of data.
- 39MultimodalDescription of a distribution of observations that has more than two modes.
- 40Negative SkewWhen the frequent scores are clustered at the higher end of the distribution and the tail points towards the lower more negative scores.
- 41Nominal VariableWhere numbers merely represent names. For example, the numbers on sports players shirts. The numbers have no meaning other than denoting the type of player.
- 42NonileA type of quantile; they are values that split the data into nine equal parts. They are commonly used in educational research.
- 43Normal DistributionA probability distribution of a random variable that is known to have certain properties. It is perfectly symmetrical (has a skew of 0), and has a kurtosis of 0.
- 44Ordinal VariableData that tells us not only that things have occurred, but also the order in which they occurred. These data tells us nothing about the differences between values. For example, gold, silver, and bronze medals are ordinal; they tell us that the gold medallist was better than the silver medallist, but they don't tell us how much better (was gold a lot better than silver, or were gold and silver closely competed?)
- 45Outcome VariableA variable whose values we are trying to predict from one or more predictor variables.
- 46PercentileA type of quantile; they are values that split data into 100 equal parts.
- 47PlatykurticA distribution with negative kurtosis has too few scores in the tails and is quite flat.
- 48Positive SkewWhen the frequency scores are clustered at the lower end of the distribution and the tail points towards the higher or more positive skews.
- 49Practice EffectRefers to the possibility that participants' performance in a task may be influenced (positively or negatively) if they repeat the task because of familiarity with the experimental situation and/or the measure being used.
- 50Predictive ValidityA form of criterion validity where there is evidence that score from an instrument predict external measures (recorded at a different point in time) conceptually related to the measured construct.
- 51Predictor VariableA variable that is used to try to predict values of another variable known as an outcome variable.
- 52Probability Density Function (PDF)The function that describes the probability of a random variable taking a certain value. It is the mathematical function that describes the probability distribution.
- 53Probability DistributionA curve describing an idealized frequency distribution of a particular variable from which it is possible to ascertain the probability with which specific values of that variable will occur. For categorical variables it is simply a formula yielding the probability with which each category occurs.
- 54Qualitative MethodsExtrapolating evidence for a theory from what people say or write.
- 55Quantitative MethodsInferring evidence for a theory through measurement of variables that produce numeric outcomes.
- 56QuantileValues that split a data set into equal portions. Are a special case of quantiles that split the data into four equal parts.
- 57QuartileA generic term for the three values that cut an ordered data set into four equal parts. The three quartiles are known as the lower quartile, the second quartile (or median), and the upper quartile.
- 58RandomizationThe process of doing things in an unsystematic or random way. In the context of experimental research then word usually applies to the random assignment of participants to different treatment conditions.
- 59RangeThe range of scores is the value of the smallest score subtracted from the highest score. It is a measure of the dispersion of a set of scores.
- 60Ratio VariableAn interval variables but with the additional property that rations are meaningful. For example, people's rating of this book on Amazon.com can range from 1 to 5; the data must have the properties of interval variables, but in addition a rating of 4 should genuinely represent someone who enjoyed this book twice as much as someone who rated it as 2. Likewise, someone who rated it as 1 should be half as impressed as someone who rated it as 2.
- 61ReliabilityThe ability of a measure to produce consistent results when the same entities are measured under different conditions.
- 62Repeated-Measures DesignAn experimental design in which different treatment conditions utilize the same organisms (i.e., in psychology this would mean the same people take part in all experimental conditions) and so the resulting data are related (a.k.a related design or within-subject design).
- 63Second QuartileAnother name for the median.
- 64SkewA measure of the symmetry of a frequency distribution. Symmetrical distributions have a skew of 0.
- 65Standard DeviationAn estimate of the average variability (spread) of a set of data measured in the same units of measurement as the original data. It is the square root of the variance.
- 66Systematic VariationVariation due to some genuine effect (be it the effect of an experimenter doing something to all of the participants in one sample but not in other samples, or natural variation between sets of variables). We can think of this as variation that can be explained by the model that we're fitted to the data.
- 67Sum of Squared ErrorsAnother name for the sum of squares.
- 68Tertium QuidThe possibility that an apparent relationship between two variable is actually caused by the effect of a third variable on them both (often called the third-variable problem).
- 69Test-Retest ReliabilityThe ability of a measure to produce consistent results when the same entities are tested at two different points in time.
- 70TheoryAlthough it can be defined more formally, a theory is a hypothesized general principle or set of principles that explain known findings about a topic and from which new hypotheses can be generated.
- 71Unsystematic VarianceThis is variation that isn't due to the effect in which we're interested (so could be due to natural differences between people in different samples such as differences in intelligence or motivation). We can think of this as variation that can't be explained by whatever model we've fitted to the data.
- 72Upper QuartileThe value that cuts off the highest 25% of ordered scores. If the scores are ordered and then divided into two halves at the median, then the upper quartile is the median of the top half of the scores.
- 73ValidityEvidence that a study allows correct inferences about the question it was aimed to answer or that a test measures what it set out to measure conceptually.
- 74VariablesAnything that can be measured and can differ across entities or across time.
- 75VarianceAn estimate of average variability (spread) of a set of data. It is the sum of squares divided by the number of values on which the sum of squares is based minus 1.
- 76Within-Subject DesignAnother name for a repeated-measures design.
- 77Z-scoresThe value of an observation expressed in standard deviation units. It is calculated by taking the observation, subtracting from it the mean of all observations, and dividing the result by the standard deviation of all the observations. By converting a distribution of observations into z-scores a new distribution is created that has a mean of 0 and a standard deviation of 1.
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- Psychology Flashcards on Stats Chapter 1, created by Sarah Church on 07/10/2016.
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- Sarah Church
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