PSY 2100 Final Exam Review Questions With
Complete Answers
What is central tendency? - ANSWER Refers to the typicalness or representativeness of
a distribution.
What are the three indicators of central tendency? - ANSWER The mean, median and
mode.
What are the two important properties of the mean? - ANSWER (a) Deviations about the
mean: The sum of deviations of scores about their mean is zero.
(b) Minimum variability of scores about the mean: least squares sense.
What is the median? - ANSWER The point on the measurement scale that divides the
distribution into two parts such that equal numbers of scores lie above and below that
point.
What is the mode? - ANSWER The most frequently occurring score value.
What are the characteristics of the 3Ms? - ANSWER They are not always the same value:
may differ depending on certain aspects of a data set.
What is an example of the 3Ms? - ANSWER The presence of outlier (extreme score).
What is true about the 3Ms? - ANSWER They are identical when the distribution is
symmetrical and unimodal (one mode) => normal distribution (bell-shaped curve).
What is the mean? - ANSWER Usually preferred to as the measure of central tendency.
,What are the benefits of the mean? - ANSWER It is easy to communicate and is required
for many statistical procedures.
What is true about the median? - ANSWER It may be substituted when the distribution is
greatly skewed (or when there is an outlier).
What is true about the mode? - ANSWER It is most often used as a supplement to the
mean or median
What is an example of a variability? - ANSWER A = {3,4,5,6,7} vs. B = {1,2,5,8,9}
What is range? - ANSWER The largest - the smallest
What is an example of a range? - ANSWER A = {1,2,3,7,8,9} vs. B = {1,5,5,5,5,9}
What is variance? - ANSWER The average sum of squared deviations of scores about
the mean.
What is standard deviation? - ANSWER The positive square root of the variance.
What is an example of standard deviation? - ANSWER The calculation of variance and
standard deviation.
Why standard deviation? - ANSWER - Remember variance has a "squared value"
- We need to use the original unit of measurement for better communication (ex. SAT
scores)
What are the properties of variance (SD)? - ANSWER (a) s2 and s are (almost) always
positive
(b) Variance is very sensitive to departures from the mean, because the deviations,
,when squared, become disproportionally large
(c) In case of no variability (all scores are the same value), the variance and SD are both
zero.
(d) Under some conditions, variance can be partitioned and its portions can be
attributed to different sources => will be explained in detail when we cover ANOVA
What is the variance and mean of this data set? - ANSWER Variance of {3,5,6,7,9} =>
2.23 (Mean: 6.00)
Variance of {3,5,6,7,14} => 4.18 (Mean: 7.00}
What does statistics allow for us to do? - ANSWER Allows us to generalize the results
from a small group of subjects to a much larger group.
What is population? - ANSWER A collection of subjects, events, or scores that have
some common characteristics of interest.
What is sample? - ANSWER A subgroup of a population.
How can we justify generalization? - ANSWER - Random sampling
- Good enough sample size => allows us to assume that the distribution is normal
What is the central limit theorem? - ANSWER If a population has a finite variance and
mean, the distribution of a sample approaches a normal distribution as the sample size
(N) increases.
What is true about the central limit theorem? - ANSWER Regardless of the population
distribution, if sample size N is large enough, the normal distribution is a good
approximation to the sample distribution.
What is statistic? - ANSWER A quantitative characteristic of a sample (symbolized with a
Roman letter).
, What are examples of statistics? - ANSWER X, s2, etc.
What is a parameter? - ANSWER A quantitative characteristic of a population
(symbolized with a Greek letter).
What are examples of parameters? - ANSWER µ, ß, etc.
Why SPSS? - ANSWER - Powerful tool for data management & analysis
- Compatibility with advanced stat programs such as LISREL, AMOS, etc.
Other stat packages other than SPSS? - ANSWER SAS, R, SYSTAT, SIX SIGMA, etc.
What three major windows does SPSS for windows have? - ANSWER Data Editor: the
first window, manages data
Syntax: if you opt to not use the menu
Output: automatically pops up when you run a command
What are the three major running tools for an SPSS program? - ANSWER Getting the
data, making an adjustment and running a command.
What is the data stage in an SPSS? - ANSWER - Create a new data file by encoding your
data
- Open an existing SPSS data file
- Bring the data from an MS Excel program You can copy and paste from MS Excel
*You can copy and paste from MS Excel
What is the adjustment stage for an SPSS when it comes to adjusting your data? -
ANSWER (ex) coding error - add, subtract, multiply, etc.
Complete Answers
What is central tendency? - ANSWER Refers to the typicalness or representativeness of
a distribution.
What are the three indicators of central tendency? - ANSWER The mean, median and
mode.
What are the two important properties of the mean? - ANSWER (a) Deviations about the
mean: The sum of deviations of scores about their mean is zero.
(b) Minimum variability of scores about the mean: least squares sense.
What is the median? - ANSWER The point on the measurement scale that divides the
distribution into two parts such that equal numbers of scores lie above and below that
point.
What is the mode? - ANSWER The most frequently occurring score value.
What are the characteristics of the 3Ms? - ANSWER They are not always the same value:
may differ depending on certain aspects of a data set.
What is an example of the 3Ms? - ANSWER The presence of outlier (extreme score).
What is true about the 3Ms? - ANSWER They are identical when the distribution is
symmetrical and unimodal (one mode) => normal distribution (bell-shaped curve).
What is the mean? - ANSWER Usually preferred to as the measure of central tendency.
,What are the benefits of the mean? - ANSWER It is easy to communicate and is required
for many statistical procedures.
What is true about the median? - ANSWER It may be substituted when the distribution is
greatly skewed (or when there is an outlier).
What is true about the mode? - ANSWER It is most often used as a supplement to the
mean or median
What is an example of a variability? - ANSWER A = {3,4,5,6,7} vs. B = {1,2,5,8,9}
What is range? - ANSWER The largest - the smallest
What is an example of a range? - ANSWER A = {1,2,3,7,8,9} vs. B = {1,5,5,5,5,9}
What is variance? - ANSWER The average sum of squared deviations of scores about
the mean.
What is standard deviation? - ANSWER The positive square root of the variance.
What is an example of standard deviation? - ANSWER The calculation of variance and
standard deviation.
Why standard deviation? - ANSWER - Remember variance has a "squared value"
- We need to use the original unit of measurement for better communication (ex. SAT
scores)
What are the properties of variance (SD)? - ANSWER (a) s2 and s are (almost) always
positive
(b) Variance is very sensitive to departures from the mean, because the deviations,
,when squared, become disproportionally large
(c) In case of no variability (all scores are the same value), the variance and SD are both
zero.
(d) Under some conditions, variance can be partitioned and its portions can be
attributed to different sources => will be explained in detail when we cover ANOVA
What is the variance and mean of this data set? - ANSWER Variance of {3,5,6,7,9} =>
2.23 (Mean: 6.00)
Variance of {3,5,6,7,14} => 4.18 (Mean: 7.00}
What does statistics allow for us to do? - ANSWER Allows us to generalize the results
from a small group of subjects to a much larger group.
What is population? - ANSWER A collection of subjects, events, or scores that have
some common characteristics of interest.
What is sample? - ANSWER A subgroup of a population.
How can we justify generalization? - ANSWER - Random sampling
- Good enough sample size => allows us to assume that the distribution is normal
What is the central limit theorem? - ANSWER If a population has a finite variance and
mean, the distribution of a sample approaches a normal distribution as the sample size
(N) increases.
What is true about the central limit theorem? - ANSWER Regardless of the population
distribution, if sample size N is large enough, the normal distribution is a good
approximation to the sample distribution.
What is statistic? - ANSWER A quantitative characteristic of a sample (symbolized with a
Roman letter).
, What are examples of statistics? - ANSWER X, s2, etc.
What is a parameter? - ANSWER A quantitative characteristic of a population
(symbolized with a Greek letter).
What are examples of parameters? - ANSWER µ, ß, etc.
Why SPSS? - ANSWER - Powerful tool for data management & analysis
- Compatibility with advanced stat programs such as LISREL, AMOS, etc.
Other stat packages other than SPSS? - ANSWER SAS, R, SYSTAT, SIX SIGMA, etc.
What three major windows does SPSS for windows have? - ANSWER Data Editor: the
first window, manages data
Syntax: if you opt to not use the menu
Output: automatically pops up when you run a command
What are the three major running tools for an SPSS program? - ANSWER Getting the
data, making an adjustment and running a command.
What is the data stage in an SPSS? - ANSWER - Create a new data file by encoding your
data
- Open an existing SPSS data file
- Bring the data from an MS Excel program You can copy and paste from MS Excel
*You can copy and paste from MS Excel
What is the adjustment stage for an SPSS when it comes to adjusting your data? -
ANSWER (ex) coding error - add, subtract, multiply, etc.
