Statistics Chapter 3

Question 1

What does this symbol mean f?

Answer 1

f = Simple frequency distribution

Question 2

What does this symbol mean rel.f?

Answer 2

rel.f = relative frequency

Question 3

What does this symbol mean cf?

Answer 3

cf = culmulative frequency

Question 4

What is the difference between a bar graph and a histogram and with what kind of data is each used?

Answer 4

A bar graph is a vertical bar is centered over each score on the X axis and adjacent bars do not touch and are used for a frequency distribution of nominal and ordinal scores. A histogram the adjacent bars touch and it is used for interval and ratio scores.

Question 5

What is the difference between a histogram and a polygon and with what kind of data is each used?

Answer 5

A histogram has a bar above each score and used with few different interval or ratio score. A polygon has datapoints above the scores that are connected by straight lines and is used with a whole wide range of interval/ratio scores.

Question 6

What is the difference between a score’s simple frequency and its relative frequency?

Answer 6

A simple frequency distribution shows the frequency of each score. A relative frequency is the proportion of time that the score occurred.

Question 7

What is the difference between a score’s culmination frequency and its percentile?

Answer 7

Culminating frequency is the frequency of all scores at or below the score and the percentile is the percent of all scores at or below a given score.

Question 8

What is the advantage of computing relative frequency instead of a simple frequency?

Answer 8

Relative frequency (the proportion of time a score occurs) may be easier to interpret than simple frequency (the number of times occurs).

Question 9

What is the advantage of computing percentile instead of culminative frequency?

Answer 9

Percentile may be easier to interpret than a culminative frequency.

Question 10

What is the difference between a skewed distribution and a normal distribution?

Answer 10

A skewed distribution is similar to normal distribution except that it has only one pronounced tail and can be positive or negative skewed. The normal distribution has the form of a bell and it is normal distributed.

Question 11

What is the difference between bimodal distribution and a normal distribution?

Answer 11

A bimodal distribution is a symmetrical distribution containing two distinct bumps, each reflecting high frequency scores, unlike the normal distribution which has only one distinct bump with one high frequency score.

Question 12

What does a rectangular distribution indicate instead of a culminative frequency?

Answer 12

A rectangular distribution is s symmetrical distribution in a shape of a rectangle which has no discernible tails since the frequencies of all scores are the same.

Question 13

What is the difference between a positively skewed distribution and a negatively skewed distribution?

Answer 13

A negatively skewed distribution has only one tail at the extreme low scores; a positively skewed distribution has only one tail at the extreme high scores.

Question 14

What is the difference between graphing a relationship and graphing a frequency distribution?

Answer 14

The graph showed the relationship where,as scores on the X variable change, scores on the Y variable change. A frequency distribution showed a relationship where, as X scores change, their frequency shown on Y changes.

Question 15

What does it mean when a score is in a tail of a normal distribution?

Answer 15

It means that the score is either a high or low extreme score that occurs relatively infrequently.

Question 16

The distribution of scores on your statistics test is positively skewed. What does this indicate about the difficulty of the test?

Answer 16

It indicates that the test was difficult for the class, because most often the scores are low or middle scores, and seldom there are high scores.

Question 17

Interpret: “The IQ scores were approximately normally distributed.”

Answer 17

The middle IQ score has the highest frequency in a symmetric distribution; the higher and the lower scores have lower frequencies, and the highest and the lowest scores have relatively low frequency.

Question 18

Interpret: “A bimodal distribution of physical agility scores was observed.”

Answer 18

The agility scores form a symmetric distribution containing two distinct “humps” where there are two scores that occur more frequently than the surrounding scores.

Question 19

Interpret: “The distribution of the patients’ memory scores was severely negatively skewed.”

Answer 19

The memory scores for. An asymmetric distribution in which there are some very infrequent, extremely low scores, debut there are not correspondingly infrequent high scores.

Question 20

Interpret: In a small sample, you scored at the 35th percentile.

Answer 20

35% of the sample scored at or below the score.

Question 21

Interpret: Your score has a rel. f of 0.40.

Answer 21

The score occurred 40% of the time.

Question 22

Interpret: Your score is in the upper tail of the normal curve.

Answer 22

It is one of the highest and least frequent scores.

Question 23

Interpret: Your score is in the left hand tail of the normal curve.

Answer 23

It is one of the lowest and least frequent scores.

Question 24

Interpret: Your score has a cf 50.

Answer 24

50 participants had either your score or below the score.

Question 25

Interpret: From the normal curve, your score is at the 60th percentile.

Answer 25

60% of the area under the curve and thus 60% of the distribution is on the left of (below) your score.

Question 26

What does this symbol mean N?

Answer 26

N = the number of scores in the data.

Question 27

Describe each scale of measurement.

Answer 27

Nominal - scores are names of categories.
Ordinal - scores indicate rank order, no zero, adjacent scores not equal distances.
Interval - scores indicate amounts, zero is not none, negative numbers allowed.
Ratio - scores indicate amounts, zero is none, negative numbers not allowed.

Question 28

What type of graph should you create when counting the frequency of the brands of cell phones owned by students?

Answer 28

A bar graph because this is a nominal variable.

Question 29

What type of graph should you create when counting the frequency of the different body weights reported in a statewide survey?

Answer 29

Polygon because we will have many different ratio scores.

Question 30

What type of graph should you create when counting the frequency of the people falling into one of eight salary ranges?

Answer 30

Histogram because we will only have 8 different ratio scores.

Question 31

What type of graph should you create when counting the frequency of the number of students who were absent from a class either at the beginning, middle or end of the semester?

Answer 31

Bar graph because this is an ordinal variable.