Quiz 2 Flashcards
What is a nominal scale?
A scale whose numbers serve only as labels or tags for identifying and classifying objects with a strict one-to-one correspondence between the numbers and the objects eg. medicare numbers.
What is an ordinal scale?
A ranking scale in which numbers are assigned to indicate the relative extent to which they possess some characteristic eg. market position.
What is an interval scale?
A scale in which numerically equal distances represent equal values in the characteristic being measured, eg. attitudes and opinions
What is a ratio scale?
A scale that allows the researcher to identify or classify objects, rank order the objects, compare intervals or differences and compute ratios of scale values.
Instead of using one of the four scales of measurement (nominal, ordinal, interval or ratio), what are the two other ways?
- Metric data
* Categorical data
What is metric data?
Data which includes interval and ratio. It is numeric and is measured on some sort of comparative scale - eg. how old are you in years?
What is categorical data?
Includes nominal and ordinal data and groups possible responses into two or more separate categories, eg. are you male or female?
Can data fit into both metric and categorical categories?
Yes, age, can be metric, 10 years old or categorical in a 0-18 year category.
The data produced from a multi-item scale such as a Likert scale produces what sort of data?
Individual questions are categorical, but the rating applied by averaging the responses is metric.
What is a frequency table?
A tabulation of how many times each of the possible responses was recorded.
What is a pie chart?
A graphical representation of data where the number of categories is not too large and no individual category is too small.
When writing a report what information should always be mentioned?
- the sample size
- percentages
- Interesting aspects of the responses
- type of tests applied
- the middle
- the spread
- the shape
What is important to remember in capturing results?
Do not speculate - keep it fact based, speculation is for the discussion section.
What are the rules of using a histogram?
- No space between the bars
* Each category must be the same size
What is the difference between a bar chart and a histogram?
- Bar charts use categorical data on the x axis
* There are gaps between the bars on a bar chart.
What are the key parts of a histogram or data that need to be described?
- The Middle
- The Spread
- The Shape
What are the descriptors of the middle of a data set?
- Mean
- Mode
- Median
What is the Mean?
The average - the value obtained by summing all elements in a set and dividing by the number of elements
What is the Mode?
Is a measure of central tendency given as the value that occurs the most n the sample distribution.
What is the Median?
It is a measure of the most central tendency given as the value above which half of the values fall and below which half of the values fall.
What are the descriptors of the spread of a data set?
- Range
- Percentile
- First quartile
- Interquartile range
- Variance
- Standard deviation
What is the range?
The difference between the largest and smallest values of a distribution.
What is the Percentile?
These are values below which a certain percentage of the data lies, eg. the 30th percentile had 30% of the data beneath it.
What is First Quartile?
This is the first quarter (25th Percentile) of the data.
What is the interquartile range?
It is the range of a distribution encompassing the middle 50% of the observations, eg from 25th to 75th percentile.
What is variance?
It is the mean squared deviation of all the values from the mean.
What is standard deviation and what is the important rule with standard deviation?
Is the square root of the variance. At least 75% of all data will be within 2 standard deviations of the mean and at least 88.89% of all data within 3 standard deviations of the mean.
What are the options for the shape of the data set?
Symmetrical (where mean = median)
Negative skewed - where mean is lower than the median
Positive skewed - where mean is higher than the median.
When writing your report, what is the rule to use if the distribution is skewed?
Refer to the median & quartiles not the mean and standard deviation
What is descriptive statistics?
A term used to describe how statistics are looking and is the basic way data is described.
Categorical data can be classified into what two categories?
- Ordinal data - can be classified and ranked
* Nominal data - values and observations can be classified but cannot be ranked.