Module 15: Data Organization, Central Tendency, and Variance

Question 1

Frequency distribution

Answer 1

a table in which all of the scores are listed along with the frequency with which each occurs

Question 2

Relative frequency

Answer 2

can be multiplied by 100 to get a percentage

Question 3

Class interval frequency distribution

Answer 3

can be created for larger data sets. we combine individual scores into categories, or intervals, and list them along with the frequency of scores in each interval.

Question 4

Graphs

Answer 4

Sometimes a picture is of greater value than frequency distributions. The most common graphs used are:

• Bar graph
• Histogram
• Frequency polygons

Question 5

Bar graph

Answer 5

a graphical representation of a frequency distribution in which vertical bars are centered above each category along the x-axis and are separated from each other by a space, which indicates that the levels of the variable represent distinct, unrelated categories.

Question 6

Qualitative variable

Answer 6

a categorical variable for which each value represents a discrete category

Question 7

Statistics

Answer 7

refers to a range of techniques and procedures for analyzing, interpreting, displaying, and making decisions based on data.

Question 8

Histogram

Answer 8

a graphical representation of a frequency distribution in which vertical bars are centered above scores on the x-axis, but in a histogram the bars touch each other to indicate that the scores on the variable represent related, increasing values. A histogram is more useful when the data collected are on an ordinal, interval or ratio
scale

Question 9

Quantitative variable

Answer 9

the scores represent a change in quantity

Question 10

Frequency polygons

Answer 10

a line graph of the frequencies of individual scores, this is a type of histogram. Frequency polygons are appropriate when the variable is quantitative or the data are ordinal, interval, or ratio. In this respect frequency polygons are similar to histograms. They are especially useful for continuous data (such as age, weight, or time) in which it is theoretically possible for values to fall anywhere along the continuum.

Question 11

Descriptive statistics

Answer 11

Are numerical measures that describe a distribution by providing information on:

• central tendency
• width
• shape

Question 12

Inferential statistics

Answer 12

generalizing from observed data to a statistical population: all the data that could have been observed.

Question 13

Hypothesis testing

Answer 13

what conclusions do the data permit considering statistical hypotheses about the population?

Question 14

Estimation

Answer 14

what do the data suggest about plausible values in the population?

Question 15

P-value

Answer 15

the probability of obtaining the sample results or even more extreme results under the assumption that the null-hypothesis is true.

Question 16

Significance level (alpha)

Answer 16

the largest admissible value of the p-value that leads to rejecting of the null-hypothesis.
• Standard: 5% (.05)
• So, we reject H0 if p < .05

Question 17

Significance

Answer 17

the value of the p-value is smaller than the value of α. So p < .05

Question 18

Measure of central tendency

Answer 18

is a representative number that characterizes the ‘middleness’ of an entire set of data. Three types:

• Mean
• Median
• Mode

Question 19

Mean

Answer 19

the arithmetic average of a group of scores, or (easier) adding everything up and dividing it by the total number of scores. The mean is appropriate for interval and ratio data, but not for ordinal or nominal data.

Question 20

Median

Answer 20

is the middle score in a distribution after the scores have been arranged from highest to lowest or lowest to highest and is used when the mean might not be representative of a distribution, for example when there are extreme highs and lows. These might influence the average.

Question 21

Mode

Answer 21

the score in a distribution that occurs with the greatest frequency

Question 22

Measure of variation

Answer 22

• Range
• Standard deviation
• Variance

Question 23

Range

Answer 23

the difference between the lowest and the highest scores in a distribution. In this simple measure of variation, however, only the highest and lowest scores enter the calculation, and all other scores are ignored. Consequently, the range is easily distorted by one unusually high or low score in a distribution.

Question 24

Standard deviation

Answer 24

is the average distance of all the scores in the distribution from the mean or central point of the distribution. An estimate of the standard deviation can also be made, however the group you are dividing with will receive 1 minus point to make the standard deviation more accurate.

Question 25

Variance

Answer 25

the standard deviation squared