Research Design Flashcards
What is the concept in measurement process?
level of abstraction -> explore relationship -> define measurement -> operationalisation -> stats test -> check replicaibility
What is categorical data?
- variables with discrete number of response options
- coded as integers
- Binary when only two values available
What is numerical data?
- continuous data with real number of value
- within specified range of measurement
Name the three types of Numerical data
- interval or ratio
- continuous
- discrete
What is count data?
variables take non-negative values
limitless but limited in lower bound
What is Nominal data?
- Binary or categorical variable
- Numbers share no relationship
- No meaningful order
What is ordinal data?
- Binary or categorical in meaningful order
- data on a scale
- use inequalities but can’t state how much; subjectivity between meanings
What is interval data?
- Interval = variables where numerical values have meaning
- no true 0 point due to continuous numerical scale
- differences have 0 point
- can add and subtract
What is ratio data?
- Variables with numerical values have meaning
- Variables have 0 point
- Plausible to divide and multiply
- Double from scale of 0
What is tidy data?
each variable in own column and each observation in own row
What are central tendency?
Averages
- set of statistics which describe central point of frequency distributions
What are dispersions?
- set of statistics describing variation in frequency distributions
What are the dispersions within nominal data?
- Central tendency = mode
- Variability = relative frequency
What are the central tendency and dispersions within ordinal data?
- central tendency = mode or median
- variability = range, inter-quartile range
What does a frequency table show?
- Possible outcomes
- Count of number of observations per outcome
- count as percentage
What is the mode?
the most observed value in data set
What is the median?
- Value for which half the data falls above and half below the given value
What is the interquartile range?
difference between the 1st and 3rd quartile
What are the steps to calculate the IQR?
- Rank the data
- Split the data into 4 equal blocks
- quartiles = points dividing ordered ranks
- IQR = difference between 25% and 75%
What does each percentage represent in IQR?
First quartile is first category = cumulative percentage ≥ 25%
Median is first category = cumulative percentage ≥ 50%
Forth quartile is first category = cumulative percentage ≥ 75%
What is cumulative frequency?
another way of expressing frequency distribution
What is used to describe nominal data?
- Bar plots
- Mode
- Frequency tables
What is used to describe ordinal data?
- Bar plots
- Mode or median
- Range (simple and IQR)
What central tendency is used to describe continuous data?
Mean: sum of all values divided by total number of observations
What is the dispersion used for continuous data
variance
standard deviation
