Chapter 4 and 5 SQs

When all the scores in a set of data are the same, what is S^2x

0

In a roughly normal distribution, the standard deviation takes approximately what value?

1/6 of the range

What is the range of the following data set: 15,9,17,12,15,19,18,15,16,10,13

10

A group of 10 students participated in a study of nutritional awareness. What is the sample standard deviation (Sx) of their scores? Their scores follow: 20,19,22,20,15,18,15,21,19,20

2.21

Find the mode of the following data set: 8,7,2,4,4,8,2,4,6,5,7,3,9,4,5,4,7

4

A group of 10 students participated in a study of nutritional awareness. what is the sample variance ( S^2x) of their score? 20,19,22,20,15,18,15,21,19,20

4.89

Find the median of the following data set: 2,2,3,4,4,4,4,4,5,5,6,7,7,7,8,8,9

5

Find the mean of the following data set: 8,7,2,4,4,8,2,4,6,5,7,3,3,9,4,5,4,7

5.24

In general what is the relationship between the value of the standard deviation and the shape of the distribution>

68-95-99 rule

When we graph results from an experiment where the independent variable is on a nominal scale, which type of graph is appropriate ?

A Bar graph

An experimenter investigated the ability to concentrate as a function of eye color. Eye color was classified as having either blue eyes, brown eyes, or the other eye color. Which type of graph should the experimenter use to display the results?

Bar graph

Why is the median unaffected by extreme scores occurring in only one tail of the distribution?

Because it is the score at the 50th percentile, 1/2 way through the data

When computing the variance, why do we square the deviations from the mean?

Because it removes all negative signs

Why are Sx and S^2x considered biased estimates for the population standard deviation and variance?

Because they underestimate the score since it is an estimate for the pop

A score's deviation conveys two pieces of information about the score's location: the number indicates ______, and the sign indicates __________.

Distance from the mean and the direction from the mean

When we refer to a score's deviation, to what are we referring?

Indicates how much a score deviates from the mean

What is the definition of the sample standard deviation

Is the square root of the sample variance

What is the best predictor of an individual score in a sample of scores?

It is the mean of the sample scores

unbiased estimators sx and s^2x of the population parameters will produce values that are ______ than those produced by the biased estimators Sx and S^2x

Larger

MU is the symbol for the _______

Population mean

When a distribution's mode>median>mean, it is said to be ________ skewed

Positively

S^2x is used to describe ______; s^2x is used to describe ________; 0^2x describes ____________.

Sample variance; the population variance (uses degrees of freedom); the population variance

S^2x is the symbol for _________

Simple variance

The distribution of weights of men in american population is not symmetrical. Most weights are bunched together at the lower end of the distribution. As weights increase, there are fewer and fewer men with these weights. How would you describe the relationship between the mean, the median, and the mode in this distribution?

The mean would be towards the higher number of men, so the lower end of the distribution

Which measure of central tendency should a researcher use to describe the sex of participants in a study?

The mode

The range is the descriptive statistic that indicates what

The range is the highest-the lowest score

What do S^2x, s^2x and 0^2x have in common?

They are all forms of variance

What are the measures of variability used to do?

Used to describe how spread out a distribution is. Shows the differences between the scores.

To obtain the mean, what steps would we follow?

You add up all of the scores and divide it by the number of scores

When is the mean the preferred measure of central tendency?

You use the mean to summarize a normal or approx normal distribution

The quantity N-1 has a special name. it is known as the _______

degrees of freedom

When deciding which type of measure of central tendency is appropriate, we consider the scale of measurement used to measure the ________

dependent variable

In order to decide which measure of central tendency is appropriate, what must you first determine?

first, the scale of measurement that is being used so that the summary makes sense given the nature of the squares. second, The shape of the frequency distribution the scores produce so that the measure accurately summarizes the distribution.

In a graph of the relationship between the level of noise in an environment and the number of errors a person makes, the ____ is on the x axis and the ______ is on the Y axis

level of noise & the number of errors

The variance and the standard deviation indicate how much the scores are spread out around the ________

mean

Which measure of central tendency is appropriate if the shape of the distribution is severely skewed

median

Of the three kinds of variance which uses N-1 in the final division?

s^2x

When it is impossible to obtain all the scores in a population, the best estimate of the population mean is the _________

sample mean

What is the definition of sample variance

the average of the squared deviations of scores around the sample mean