What is descriptive statistics?

It describes,oorganizes and summarizes data.

What does descriptive statistics consist of?

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- Central tendencies (mean, median, mode)
- Measures of dispersion (range, variance, deviation)

What is inferential statistics?

It makes generalizations about certain populations based on data from samples of that population.

What is the "mean"?

It is the average.

How do you find the mean?

Add all scores and divide by the total number of values.

What is the most commonly used centeral tendency statistic?

The mean.

what is this symbol for?

x̅

It is the symbol for mean.

It is called X bar

What does this symbol mean?

∑

Sum of values

What is mean very sensitive to?

It is very sensitive to extreme values or "outliers"

What is the median?

It is the middle score in a list of data values.

What should you do if you have an even number of scores when trying to find the median?

The median is halfway between the two middle scores.

**It doesn't have to match a score.**

How are values set up when trying to find the median?

The values are put in numerical order to find the median.

What is mode?

It is the most reoccuring score.

What is the mode most useful for?

It is most useful for nominal data

What is an outlier?

an observation point that is distant from other observations.

What are some measures of dispersion?

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- Range
- Variance
- Standard deviation
- Normal distribution
- Bell curve
- (+/-) skewed distributions

How do you find the range?

Highest score-lowest score

Describe the stability of range?

It is an **unstable **measurement since it takes outliers into account and takes only two values into account.

What is the variance?

It is a measurement of how far a set of data extends from the mean.

What is the standard deviation?

It is the most commonly reported measurements of dispersions--how far part the values are spread.

How do you find the standard deviation?

It is the square root of the variance.

What does a small SD indicate?

Less variability in values and the fewer 'n' needed.

What is the standard deviation susceptible to?

Outliers

What is normal distribution?

It equals the same mean, median and mode.

**Symmetrical data.**

What is bell curves commonly used for?

To plot grades.

What makes a distribution negatively skewed?

It is distribution that is negatively skewed, or skewed to the left, if the scores fall towards the higher side of the scale and there are very few low scores.

What makes a distribution positively skewed?

The mean is usually larger than the median, which is aways greater than mode.

What is anther way to mesure variance?

Standard error

How do the values compare in SD and Standard error?

The value is smaller than standard deviation

What are 3 types of symmetrical distributions?