CNSL 503: A GUIDE TO A+. QUESTIONS AND ANSWERS
FORMAT.LATEST UPDATE
Population
collection of all individuals or items under consideration
- who we want to test
Sample
part of the population that we collect information from
- who we actually test
Parameter
represents true measure of population of interest
- Parameter = Population
Statistic
represents measure calculated from sample
- Statistic = Sample
Collect information on height on 7 students in the class of 38 and calculate the mean.
Does this represent parameter or statistic?
Statistic because you are only looking at a sample of the population
Collect information on height of all 38 students in the class and calculate the mean.
Does this represent parameter or statistic?
Parameter because you are looking at entire population
What are the three things you need to know for Descriptive Statistics?
- distribution
- measure of central tendency
- variability
Distribution
summary of frequency of individual values or ranges of values for a variable
Measure of central tendency
central point around which some of the data tend to cluster
- mean, median, mode
Variability
, how far away from the central point all the data lies
How to view distribution of data?
- number
- percentage
- frequency = bar graph, pie chart, histogram, line plot
What is the best measure of central tendency to use for nominal data?
mode
What is the best measure of central tendency to use for ordinal data?
median
What is the best measure of central tendency to use for interval/ratio skewed data?
median
What is the best measure of central tendency to use for interval/ratio unskewed data?
mean
Measures of Variability
- range
- interquartile/interpercentile range
- standard deviation
Interquartile range (IQR)
Q3 - Q1
- the middle 50% of the data
First quartile (Q1) or lower quartile
25th percentile
Second quartile (Q2) or median
50th percentile
Third quartile (Q3) or upper quartile
75th percentile
Standard deviation
a measure of variability that describes an average distance of every score from the mean
What percent of data falls within 1 standard deviation of the mean?
68%
FORMAT.LATEST UPDATE
Population
collection of all individuals or items under consideration
- who we want to test
Sample
part of the population that we collect information from
- who we actually test
Parameter
represents true measure of population of interest
- Parameter = Population
Statistic
represents measure calculated from sample
- Statistic = Sample
Collect information on height on 7 students in the class of 38 and calculate the mean.
Does this represent parameter or statistic?
Statistic because you are only looking at a sample of the population
Collect information on height of all 38 students in the class and calculate the mean.
Does this represent parameter or statistic?
Parameter because you are looking at entire population
What are the three things you need to know for Descriptive Statistics?
- distribution
- measure of central tendency
- variability
Distribution
summary of frequency of individual values or ranges of values for a variable
Measure of central tendency
central point around which some of the data tend to cluster
- mean, median, mode
Variability
, how far away from the central point all the data lies
How to view distribution of data?
- number
- percentage
- frequency = bar graph, pie chart, histogram, line plot
What is the best measure of central tendency to use for nominal data?
mode
What is the best measure of central tendency to use for ordinal data?
median
What is the best measure of central tendency to use for interval/ratio skewed data?
median
What is the best measure of central tendency to use for interval/ratio unskewed data?
mean
Measures of Variability
- range
- interquartile/interpercentile range
- standard deviation
Interquartile range (IQR)
Q3 - Q1
- the middle 50% of the data
First quartile (Q1) or lower quartile
25th percentile
Second quartile (Q2) or median
50th percentile
Third quartile (Q3) or upper quartile
75th percentile
Standard deviation
a measure of variability that describes an average distance of every score from the mean
What percent of data falls within 1 standard deviation of the mean?
68%
