Field SPSS 4th edition - chapter 1,
Stats Test #1-Graded A
Binary variable - ANSWER-a categorical variable that has only two mutually exclusive
categories (e.g., being dead or alive).
Categorical variable - ANSWER-The university you attend is a good example of a
categorical variable: students who attend the University of Sussex are not also enrolled
at Harvard or UV Amsterdam, therefore, students fall into distinct categories.
Central tendency - ANSWER-a generic term describing the centre of a frequency
distribution of observations as measured by the mean, mode and median.
Confounding variable - ANSWER-a 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.
Content validity - ANSWER-evidence that the content of a test corresponds to the
content of the construct it was designed to cover.
Continuous variable - ANSWER-a variable that can be measured to any level of
precision. (Time is a continuous variable, because there is in principle no limit on how
finely it could be measured.)
Criterion validity - ANSWER-evidence that scores from an instrument correspond with
(concurrent validity) or predict (predictive validity) external measures conceptually
related to the measured construct.
Dependent variable - ANSWER-another name for outcome variable. This name is
usually associated with experimental methodology 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.
Discrete variable - ANSWER-a variable that can only take on certain values (usually
whole numbers) on the scale.
Ecological validity - ANSWER-evidence that the results of a study, experiment or test
can be applied, and allow inferences, to real-world conditions.
Falsification - ANSWER-the act of disproving a hypothesis or theory.
,Frequency distribution - ANSWER-a 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).
Histogram - ANSWER-a frequency distribution.
Hypothesis - ANSWER-a prediction about the state of the world
Independent variable - ANSWER-another name for a predictor variable. This name is
usually associated with experimental methodology 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).
Interquartile range - ANSWER-the 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 lower
quartile.
Levels of measurement - ANSWER-the relationship between what is being measured
and the numbers obtained on a scale.
Lower quartile - ANSWER-the 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.
Measurement error - ANSWER-the discrepancy between the numbers used to
represent the thing that we're measuring and the actual value of the thing we're
measuring (i.e., the value we would get if we could measure it directly).
Negative skew - ANSWER-Conversely, when the frequent scores are clustered at the
higher end of the distribution and the tail points towards the lower more negative scores,
the value of skew is negative.
Normal distribution - ANSWER-a 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.
Outcome variable - ANSWER-a variable whose values we are trying to predict from one
or more predictor variables.
Percentiles - ANSWER-a type of quantile; they are values that split the data into 100
equal parts.
Positive skew - ANSWER-When the frequent scores are clustered at the lower end of
the distribution and the tail points towards the higher or more positive scores, the value
of skew is positive.
,Predictive validity - ANSWER-a form of criterion validity where there is evidence that
scores from an instrument predict external measures (recorded at a different point in
time) conceptually related to the measured construct.
Predictor variable - ANSWER-a variable that is used to try to predict values of another
variable known as an outcome variable.
Qualitative methods - ANSWER-extrapolating evidence for a theory from what people
say or write (cf. quantitative methods).
Quantitative methods - ANSWER-inferring evidence for a theory through measurement
of variables that produce numeric outcomes (cf. qualitative methods).
Quartiles - ANSWER-a 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.
Randomization - ANSWER-the process of doing things in an unsystematic or random
way. In the context of experimental research the word usually applies to the random
assignment of participants to different treatment conditions.
Range - ANSWER-the 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. See also
variance, standard deviation, and interquartile range.
Reliability - ANSWER-the ability of a measure to produce consistent results when the
same entities are measured under different conditions.
Second quartile - ANSWER-another name for the median.
Skew - ANSWER-a measure of the symmetry of a frequency distribution. Symmetrical
distributions have a skew of 0.
Standard deviation - ANSWER-an 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.
Sum of squared errors - ANSWER-another name for the sum of squares.
Theory - ANSWER-although 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.
Upper quartile - ANSWER-the 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.
, Validity - ANSWER-evidence 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
(see also Content validity, Criterion validity).
Variables - ANSWER-anything that can be measured and can differ across entities or
across time.
Variance - ANSWER-an 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.
z-score - ANSWER-the 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 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.
Under what circumstances would you choose the Median as a preferred measure of
central tendency? - ANSWER-The purpose for reporting the median in these situations
is to combat the effect of outliers. Outliers affect the distribution because they are
extreme scores. For example, in a distribution of peoples income, a person who has an
income of over a million dollars would dramatically increase the mean income whereas
in reality, most of the people in the distribution do not make that kind of money. In this
case, the median is the preferred measure of central tendency.
Under what circumstances would you choose the Mean as a preferred measure of
central tendency? - ANSWER-The mean is ordinarily the preferred measure of central
tendency. The mean is the arithmetic average of a distribution. The mean presented
along with the variance and the standard deviation is the "best" measure of central
tendency for continuous data.
There are some situations in which the mean is not the "best" measure of central
tendency. In certain situations, the median is the preferred measure. These situations
are as follows:
when you know that a distribution is skewed
when you believe that a distribution might be skewed
when you have a small number of subjects
Under what circumstances would you choose the Mode as a preferred measure of
central tendency? - ANSWER-The mode is rarely chosen as the preferred measure of
central tendency. The mode is not usually used because the largest frequency of scores
might not be at the center. The only situation in which the mode may be preferred over
the other two measures of central tendency is when describing discrete categorical
Stats Test #1-Graded A
Binary variable - ANSWER-a categorical variable that has only two mutually exclusive
categories (e.g., being dead or alive).
Categorical variable - ANSWER-The university you attend is a good example of a
categorical variable: students who attend the University of Sussex are not also enrolled
at Harvard or UV Amsterdam, therefore, students fall into distinct categories.
Central tendency - ANSWER-a generic term describing the centre of a frequency
distribution of observations as measured by the mean, mode and median.
Confounding variable - ANSWER-a 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.
Content validity - ANSWER-evidence that the content of a test corresponds to the
content of the construct it was designed to cover.
Continuous variable - ANSWER-a variable that can be measured to any level of
precision. (Time is a continuous variable, because there is in principle no limit on how
finely it could be measured.)
Criterion validity - ANSWER-evidence that scores from an instrument correspond with
(concurrent validity) or predict (predictive validity) external measures conceptually
related to the measured construct.
Dependent variable - ANSWER-another name for outcome variable. This name is
usually associated with experimental methodology 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.
Discrete variable - ANSWER-a variable that can only take on certain values (usually
whole numbers) on the scale.
Ecological validity - ANSWER-evidence that the results of a study, experiment or test
can be applied, and allow inferences, to real-world conditions.
Falsification - ANSWER-the act of disproving a hypothesis or theory.
,Frequency distribution - ANSWER-a 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).
Histogram - ANSWER-a frequency distribution.
Hypothesis - ANSWER-a prediction about the state of the world
Independent variable - ANSWER-another name for a predictor variable. This name is
usually associated with experimental methodology 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).
Interquartile range - ANSWER-the 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 lower
quartile.
Levels of measurement - ANSWER-the relationship between what is being measured
and the numbers obtained on a scale.
Lower quartile - ANSWER-the 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.
Measurement error - ANSWER-the discrepancy between the numbers used to
represent the thing that we're measuring and the actual value of the thing we're
measuring (i.e., the value we would get if we could measure it directly).
Negative skew - ANSWER-Conversely, when the frequent scores are clustered at the
higher end of the distribution and the tail points towards the lower more negative scores,
the value of skew is negative.
Normal distribution - ANSWER-a 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.
Outcome variable - ANSWER-a variable whose values we are trying to predict from one
or more predictor variables.
Percentiles - ANSWER-a type of quantile; they are values that split the data into 100
equal parts.
Positive skew - ANSWER-When the frequent scores are clustered at the lower end of
the distribution and the tail points towards the higher or more positive scores, the value
of skew is positive.
,Predictive validity - ANSWER-a form of criterion validity where there is evidence that
scores from an instrument predict external measures (recorded at a different point in
time) conceptually related to the measured construct.
Predictor variable - ANSWER-a variable that is used to try to predict values of another
variable known as an outcome variable.
Qualitative methods - ANSWER-extrapolating evidence for a theory from what people
say or write (cf. quantitative methods).
Quantitative methods - ANSWER-inferring evidence for a theory through measurement
of variables that produce numeric outcomes (cf. qualitative methods).
Quartiles - ANSWER-a 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.
Randomization - ANSWER-the process of doing things in an unsystematic or random
way. In the context of experimental research the word usually applies to the random
assignment of participants to different treatment conditions.
Range - ANSWER-the 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. See also
variance, standard deviation, and interquartile range.
Reliability - ANSWER-the ability of a measure to produce consistent results when the
same entities are measured under different conditions.
Second quartile - ANSWER-another name for the median.
Skew - ANSWER-a measure of the symmetry of a frequency distribution. Symmetrical
distributions have a skew of 0.
Standard deviation - ANSWER-an 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.
Sum of squared errors - ANSWER-another name for the sum of squares.
Theory - ANSWER-although 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.
Upper quartile - ANSWER-the 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.
, Validity - ANSWER-evidence 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
(see also Content validity, Criterion validity).
Variables - ANSWER-anything that can be measured and can differ across entities or
across time.
Variance - ANSWER-an 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.
z-score - ANSWER-the 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 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.
Under what circumstances would you choose the Median as a preferred measure of
central tendency? - ANSWER-The purpose for reporting the median in these situations
is to combat the effect of outliers. Outliers affect the distribution because they are
extreme scores. For example, in a distribution of peoples income, a person who has an
income of over a million dollars would dramatically increase the mean income whereas
in reality, most of the people in the distribution do not make that kind of money. In this
case, the median is the preferred measure of central tendency.
Under what circumstances would you choose the Mean as a preferred measure of
central tendency? - ANSWER-The mean is ordinarily the preferred measure of central
tendency. The mean is the arithmetic average of a distribution. The mean presented
along with the variance and the standard deviation is the "best" measure of central
tendency for continuous data.
There are some situations in which the mean is not the "best" measure of central
tendency. In certain situations, the median is the preferred measure. These situations
are as follows:
when you know that a distribution is skewed
when you believe that a distribution might be skewed
when you have a small number of subjects
Under what circumstances would you choose the Mode as a preferred measure of
central tendency? - ANSWER-The mode is rarely chosen as the preferred measure of
central tendency. The mode is not usually used because the largest frequency of scores
might not be at the center. The only situation in which the mode may be preferred over
the other two measures of central tendency is when describing discrete categorical
