Test 1

Question 1

Describe the distinction between descriptive and inferential statistics. Cite an example for each.

Answer 1

Descriptive; Describe, organize, main features. Ex: mean, median and mode.

Inferential: inferences, predictions
testing small —> large group
example: sample vs population

Question 2

Define and distinguish among nominal, ordinal, interval and ratio scales of measurement. Generate an example for each that illustrates the distinctions among the scales.

Answer 2

nominal: category, grouping names.
Example: carrying a book or not; helps separates things.

ordinal: rank <>; ex; order of finishes in a race
interval: equal distances between points, can have negative numbers. example; celcious -8degrees

ratio: absolute zero point
weight is ratio because not interval because it cant have a negative weight

Question 3

Describe the difference between discrete and continuous variables

Answer 3

discrete variable: limited number of points between any two variables on the scale.
- cant be a half number only a whole number

continuous variable: unlimited number of points between any 2 values on the scale.
example: keep adding numbers, weight

Question 4

compare and contrast the mean, median and mode in terms of their various characteristics. Explain how skewness affects the mean and the median.

Answer 4

mean: average ( a measure of central tendency where the sum of the deviations always = 0.
median: the middle number
mode: most occurring

the skewness affects the mean more than the median because there can be outliers.

Question 5

Define and identify the purposes served by standard deviation. Explain the exact relationship between the variance and the standard deviation.

Answer 5

Standard deviation:Square root of variance and its a number that tells us how much on average a group of scores deviates from the mean.
Variance: Is the mean of the squares of the individual differences from the sample mean.

SD= is the mean of the square root of the variance.

Question 6

What is the relationship between standard deviation and z scores?

Answer 6

A z score is a deviation score expressed in standard deviation. Also a Z score tells you how many standard deviations your score is away from the mean.

Question 7

What purpose is served in converting raw scores to z scores?

Answer 7

A z score allows you to compare scores from different distributions.