Chapter 4-Descriptive Results Flashcards
how is quantitative Qnt different than qualitative Qal in terms of types of variables
• Differs from Ql research in that there are two types of variables: independent (or predictor) + dependent
dependent vs independent variables Qnt
- The dependent variable is determined by the other variables in the study
- Independent variable is used to explain or predict the outcome of the dv
what is aka the predictor variable Qnt
• Independent variable (aka predictor variable)is used to explain or predict the outcome of the dv
what is variance Qnt
• Variance = the diversity of data for a single variable
o Is a number, a statistic
o = the sum of the differences between each value in the set of numbers and the mean of those numbers, divided by how many numbers there were in the set minus 1
o = the aversage of the squared deviations of the mean
hopefully not nec
how do you get variance and what value is it expresed as
o Steps: 1) Take each value and subtract the mean from it 2) Square each of those values 3) Add all of the squared values together 4) Divide that by the total number of values less 1
o Value is expressed as s^2 (squared)
o Allow for comparison of the degree of variation
which term is used more than variance in the results section
how is it shortened
• Standard Deviation
o = the square root of the variance
o Often abbreviated to “SD”
why are variance and SD important
- Why are variance + SD important? Taking a mean of two sets of data may make them seem like they’re very similar if average is the same…but having SD shows us that in one set of data there was a greater variety of data overall (for something like pain, this could mean that the pain med was less consistent in relieving pain)
- Sometimes you want high SD and sometimes low, depending on the variables
Is the following statement True or False?
The standard deviation reports how much variety or difference there is in a set of numbers.
False.
The variance reports how much variety or difference there is in a set of numbers. The standard deviation is the square root of the variance.
what is distribution
• Distribution = how the findings were dispersed
o May assign different variables a number and express them in histogram, pie chart, etc
what is frequency distribution and what does it show
o Frequency distribution = spread for how frequently each category occurs or is selected; can be seen represented as histogram. Like SD, shows distribution + variety in the variable
what shape does a normal curve have and what assumption is commonly made about distribution of a variable
• Normal curve = symmetric + bell shaped distribution
o May see something like this if plotting height
o Much of inferential statistics is based on the assumption that the distribution of a vriable would be normal if all possible values for the bariale were known
when you are measuring discrete categories like job preference what kind of distribution might you want to use
frequency distriution
or use tables of percentages, hisogram or pie chart
theyre often expressed in percents of what category people choose. you can assign numbers 1 or two to the categories but you cant work with these numbers eg subtract them because theyre just randomly assigned and meaningless
which of the following is used for numeric variable and which of the following is used for categorical variable
frequency table
histogram
standard deviation
numeric variable =SD
categorical variable=
frequency table
histogram
what does it mean when people refer to the distribution of a variable as “approximately normal”
inferential stats are often based on assumption that distribution of a variable would be normal/bell shaped if all possible values for the variable were known
is standard deviation or variance a univariate or bivariate statistic
univariate
