1S Descriptive and Inferential Stat Flashcards
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What are descriptive statistics used for?
Descriptive statistics are used to describe the basic features of the data in a study.
what are inferential statistics used for?
trying to reach conclusions that extend beyond the immediate data alone OR we use inferential statistics to make inferences from our data to more general conditions
What are descriptive statistics useful for?
Descriptive statistics help us to simplify large amounts of data in a sensible way. Each descriptive statistic reduces lots of data into a simpler summary.
What is Univariate analysis?
Univariate analysis is a form of analysis that only involves a single variable/ involves the examination across cases of one variable at a time
What is Univariate analysis part of?
descriptive statistics
Name major characteristics of a single variable
- the distribution
- the central tendency
- the dispersion
What is the distribution?
The distribution is a summary of the frequency of individual values or ranges of values for a variable.
What would list the simplest distribution?
The simplest distribution would list every value of a variable and the number of persons who had each value.
Name one of the most common ways to describe a single variable
One of the most common ways to describe a single variable is with a frequency distribution.
What are frequency distributions?
they are visual displays that organize and present frequency counts so that the information can be interpreted more easily
How frequency distributions can be depicted?
Frequency distributions can be depicted in two ways, as a table or as a graph. Distributions may also be displayed using percentages.
What is central tendency?
The central tendency of a distribution is an estimate of the “center” of a distribution of values.
Name major types of estimates of central tendency
- Mean
- Median
- Mode
What is dispersion?
Dispersion refers to the spread of the values around the central tendency.
Name two common measures of dispersion
There are two common measures of dispersion, the range and the standard deviation.
What is the range? Give an example
The range is simply the highest value minus the lowest value. In our example distribution, the high value is 36 and the low is 15, so the range is 36 - 15 = 21.
What is the disadvantage of the range?
An outlier can greatly exaggerate the range
What does the standard Deviation shows?
The Standard Deviation shows the relation that set of scores has to the mean of the sample.
How to compute the standard deviation?
To compute the standard deviation, we first (1) find the distance between each value and the mean.
Notice that values that are below the mean have negative discrepancies and values above it have positive ones.
(2) Next, we square each discrepancy: take these “squares” and sum them to get the Sum of Squares (SS) value.
(3) Next, we divide this sum by the number of scores minus 1. This value is known as the variance. To get the standard deviation, we take the square root of the variance (remember that we squared the deviations earlier).
Describe the standard deviation
the square root of the sum of the squared deviations from the mean divided by the number of scores minus one
Formula of the standard deviation
check “1S Self study Descriptive Statistics” file
When is one of the simplest inferential tests used?
Perhaps one of the simplest inferential test is used when you want to compare the average performance of two groups on a single measure to see if there is a difference
