PSY202-219419224
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Concepts:
Dependent Variable
Definition: According to the textbook, a dependent variable is a variable that is measured.
Application:In the study, the experimenters tested which DNA caused childhood obesity. As childhood obesity was the variable that was measured, childhood obesity was the dependent variable.
Nominal Variable
Definition: According to the textbook, a nominal variable is mutually exclusive and exhaustive categories differing in some qualitative aspect.
Example:http://sportsillustrated.cnn.com/football/nfl/scoreboards/today/
Application: The NFL scores and results, which means that they cannot fall into more thatn one category which makes it exclusive and there are many categories to see the observation.
Ordinal Variable
Definition: According to the textbook, an ordinal variable has the properties of a nominal scale but in addition the observation may be ranked in order of magnitude (with nothing implied about the diffeence between adjacement steps on the scale).
Example:http://sportsillustrated.cnn.com/football/nfl/standings/
Application: The NFL standings are ranked in order of magnitude and by categories.
Interval Variable
Definition: According to the textbook, an interval variable has all the properties of an ordinal scale, and a given distance between measures has the has the same meaning anywhere on the scale.
Example:http://www.ats.ucla.edu/stat/SAS/dae/intreg.htm
Application: This article does not describe the exact value of students GPA instead it describes the interval in which the GPA of students falls.
Ratio Variable
Definition: According to the textbook, a ratio variable has all the properties of an interval scale plus and absolute zero point.
Example:http://www.scholarpedia.org/article/Eye_movements
Application: In this study, the experimenters measured eye movements characteristics in reading, scene perception, and visual search. It shows a range of average fixation durations for each of the tasks.
Frequency Distribution (regular, grouped, relative, or cummulative)
Definition: According to the textbook, a frequency distribution (regular, grouped, relative, or cummulative) shows the number of observations for the possible categories or score values in a set of data.
Example:http://www.scholarpedia.org/article/Image:Balance_of_inhibition_and_excitation_figure2vb.jpg
Application: In this study, the experimenters tested the balance of inhibitional and excitation. They measured the excitatory conductance, inhibitory conductance, and the total conductance. It shows the number of observations in those possible categories.
Percentile (percentile or percentile rank)
Definition: According to the textbook, a percentile is a point on the measurement scale below which a specified percentage of the cases in a distribution falls. A percentile rank is the percentage of cases in a distribution that falls below a given point on the measurement scale.
Example:http://themorechild.com/2009/02/09/75th-percentile/
Application: The article is discussing the 75th percentile that is being used in MCPS elementary schools to determine giftedness. The 75rh percentile corresponds to an IQ of 110 that is barely above average and 129 is very superior which is in th 91st percentile.
Histogram
Definition: According to the textbook, a histogram is a graph that consists of a series of rectangles, the heights of which represent frequncy of relative frequency.
Example:http://www.une.edu.au/WebStat/unit_materials/c4_descriptive_statistics/histograms_barcharts.html
Application: the histogram shows the frequencies with bars and without spaces of collected measurements for sexparts.
Frequency Polygon
Definition: According to the textbook, a frequency polygon is a graph that consists of a series of connected dots above the midpoint of each possible class interval (height of the dots corresponds to frequncy or relative frequency).
Example:http://cnx.org/content/m10214/latest/
Application: This frequency polygon shows the psychology test scores.
Bar Diagram
Definition: According to the textbook, a bar diagram is used for qualitative data, a graph that is similar to a histogram, except that space appears between the rectangles.
Example:http://www.scholarpedia.org/article/Image:3pmodel.jpg
Application:The experimenters tested the natural history of insomnia by using qualitative data which are the following premorbid, acute insomnia, short-term insomnia, and chronic insomnia. These were measured by the following factors: perpetuating factors, precipitating factors, and predisposing factors.
Pie Chart
Definition: According to the textbook, a pie chart is used for qualitative data, area in any piece of the pie shows the relative frequency of a category.
Example:http://manyeyes.alphaworks.ibm.com/manyeyes/page/Pie_Chart.html
Application: It shows the proportions of a budget for advertising it is presented by different colors with a percentage for each.
Mean
Definition: According to the textbook, the mean is the sum of all the scores divided by the total number of scores.
Example:http://psychology.jrank.org/pages/402/Mean.html
Application: In this example they are trying to figure out the mean for heights in centimeters of fifteen children. If you sum all the heights it equals to 1995 then you take that number and you divide by fifteen you end up with a mean of 133.
Median
Definition: According to the textbook, the median is the value that divides the distribution into halves; another name for p50.
Example:http://www.nytimes.com/aponline/2009/11/23/business/AP-US-Home-Sales-Midwestern-Cities.html
Application: The median sale price for the midwest region rose one percent to $146,600. Nationally the median sale price fell seven percent to $173,100.
Mode
Definition: According to the textbook, the mode is the score that appears with the greatest frequency.
Example:http://shapefit.com/baskinrobbins.html
Application: The mode of the calories served in the Baskin Robbins include nonfat chocolate blast and sunset orange with a calorie count of 170.
Range
Definition: According to the textbook, the range is the difference between the lowest and the highest score.
Application: Juan Pierre base stealer this decade in 2004 he stole 24 times and in 2006 and 2003 he stole 20 times. the range between these scores is 4.
Variance
Definition: According to the textbook, the variance is the mean of the squares of the deviation scores.
Example:
Application:
Standard Deviation
Definition: According to the textbook, the standard deviation is the square root of the variance.
Example:
Application:
Standard Scores (z-scores)
Definition: According to the textbook, a standard deviation (z-scores)states how far away a score in from the mean in standard deviation units: one type of standard score.
Example:
Application:
Scatterplot
Definition: According to the textbook, a scatterplot is a graph of a bivariate distribution consisting of dots at the point of intersection of paired scores.
Example:http://mtsu32.mtsu.edu:11308/regression/level1/scatplot/example1.htm
Application: The scatterplot is about water consumtion based on temperature.
Correlation (r)
Definition: According to the textbook, a correlation (r) is a measure of the degree of relationship between two variables.
Example:http://news.yahoo.com/s/hsn/20091126/hl_hsn/momsdepressionmayworsenchildsasthma
Application: In the study, the experimenters tested the degree of relationship between a mother's depressive symptoms and the affects of their chldren frequent asthma symptoms and they found that there was a correlation between the two variables.
EXTRA CREDIT: Correlation does not equal causation
Examphttp://news.yahoo.com/s/hsn/20091126/hl_hsn/momsdepressionmayworsenchildsasthmale:
Mom's Depression May Worsen Child's Asthma
In this study, the experimenters tested mother's depressive symptoms and the frequent asthma symptoms for their children. The experimenters found that while the degree of a mother's depression state does affect her child's asthma symptoms the reverse was not true which means there is some correlstion but it does not equal causation.
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