1 Psychology Statistics 3010 Utah State University Exam 1

Which measure of central tendency tells you the middle score, even when the distribution is skewed?

Median

When is the Mode ALWAYS the best choice for measure of central tendency? Select all that apply.

When the data are nominal, When you want to know what score occurred most often

What do we hope to capture by using a measure of central tendency?

The typical score

This distribution has positive skew. What does that mean?

An extreme high score is making the mean higher (more positive) than the other scores would suggest

What are inter-percentile ranges (e.g., inter-quartile)?

A range of scores that fall within predetermined percentiles

Standard Deviation has what advantage over range and the inter-quartile range?

It tells deviation from the mean, rather than the distance from the ends of the distribution

What is Kurtosis?

A measure of the spread of a distribution

What do we hope to understand by looking a measure of variability?

How much the scores vary across the distribution

What does it mean to standardize a score?

To make the score unitless

What are the advantages of standardization? Select all that apply.

They don't require knowledge of the original scale to interpret size or strength, Scores can be compared across different scales (or units of measurement)

What is the general process to calculate a z-score?

Divide the distance from the mean by the standard deviation

How does a Z-score relate to the SD?

It is in units of SD; a Z-score of 1 is 1 SD from the mean

When can you compare Z-scores?

When the distributions are the same shape

What is the relation between Z-scores and probability?

For each specific distribution shape, a Z-score is associated with a certain probability of getting higher or lower than that Z score

Which of the following is true about the normal curve? Select all that apply.

 

It is theoretical and calculated from a formula, It is a family of distributions, The probability of a certain Z score is the same on any normal curve

Which Z scores cover about 68% of the normal curve?

Between -1 and +1