Psyc test 2

Which axis is the independent variable usually plotted on?

x-axis

Which axis is the dependent variable usually plotted on?

y-axis

The number of hours spent practising and the ability to successfully execute a specific skill (e.g. arm stand, high board dive) are related by a straight-line model: the more you practise, the better the performance of the dive. Which of the following equations best represents a 'straight line' model?

y=mx+c

Is it possible to calculate the skewness of a set of numerical scores?

yes

A correlation coefficient will fall within which of the following ranges?

-1 to 1

If the relationship between gender and muscular strength was r = .42, how much variability could be accounted for between the two variables?

.18

Which of the following r-values represents the weakest relationship?

.20

Typically, what is the minimum number of case per predictor?

10-15

Percentage body fat cannot be measured directly, so it has to be predicted from a series of skinfold measures. Suppose seven sites were measured (triceps, chest, midauxillary, subscapular, suprailiac, abdominal and thigh). How many participants should be recruited for a multiple regression to be performe

105

Which of the following could not be a correlation coefficient

2.7

If the R2 value for intrinsic motivation and success in performing a specific Olympic high board dive (e.g. reverse twist with pike) is +.71, how much variability can be accounted for by other variables?

29%

Using a straight line equation, calculate the potential score in a diving competition if they have amassed 250 hours of training in the 12 months leading up to the competition. Assume m = .1016 and c = 22.5.

48

A kurtosis value of -2.89 indicates

A flat and light-tailed distribution

Percentage body fat cannot be measured directly, so it has to be predicted from a series of skinfold measures. Suppose seven sites were measured (triceps, chest, midauxillary, subscapular, suprailiac, abdominal and thigh). You run a correlation matrix of the seven different skinfold sites and obtain an R value of .87 for the abdominal and subscapular sites and a variance inflation factor (VIF) of 0.1. What would you deduce from these findings?

A high degree of collinearity is likely between these two skinfold sites

What does a histogram show? (Hint: Histograms are also known as frequency distributions.)

A histogram is a graph in which values of observations are plotted on the horizontal axis, and the frequency with which each value occurs in the data set is plotted on the vertical axis.

A standard score is:

A z-score

When researching the effects of heart rate on pistol shooting, you notice a negative relationship between the two variables. Which of the following options best describes a negative relationship?

As the first variable increases, the second decreases

A researcher randomized 75 children into three groups (25 per group). Each group was taught how to perform a basketball free throw using either a visual, aural or verbal learning style. The success of the learning style was determined by the number of points scored from ten attempts. If you were to graphically present the learning style data, which might be the most appropriate option?

Bar chart

Normally distributed data are normally referred to as:

Bell-shaped

Imagine a researcher wanted to investigate whether there was a significant correlation between IQ and annual income, but she had reason to believe that work ethic would influence both of these variables. What should she do?

Conduct a partial correlation to look at the relationship between IQ and annual income while partialling out the effect of work ethic.

Which of the following is not an assumption of the general linear model?

Dependence

Which of the following best describes the variable competition status: competing versus not competing?

Dichotomous, continuous variable

How much greater is the shared variance between two variables if the Pearson correlation coefficient between them is -.4 than if it is .2?

Four times as great

Which of these variables would be considered not to have met the assumptions of parametric tests based on the normal distribution?

Gender

The central limit theorem tells us:

If the sample is large enough, the sampling distribution of a parameter will be normal.

Prior to performing a correlation test, what procedure should be performed?

Inspect a scatterplot of the data

Imagine you conduct a t-test using IBM SPSS and the output reveals that Levene's test for equality of variance is significant. What should you do?

Interpret the figures in the row labelled 'equal variances not assumed'.

Which measure of data distribution is presented as the 'box' in a box-whisker plot?

Interquartile range

The coefficient of determination:

Is a measure of the amount of variability in one variable that is shared by the other.

A correlation of .5 would produce a scatterplot in which the slope:

Is upwards (from the bottom left corner to the top right corner of the graph).

Which of the following statements about Pearson's correlation coefficient is not true?

It cannot be used with binary variables (those taking on a value of 0 or 1).

Which of the following is not a reason why multicollinearity a problem in regression?

It creates heteroscedasticity in the data.

If you have a curvilinear relationship, then

It is not appropriate to use Pearson's correlation because it assumes a linear relationship between variables

What does hierarchical regression refer to?

Known predictors of the outcome variable are entered first.

Which of the following is not a correlation test?

Kolmogorov-Smirnov

A researcher randomized 75 children into three groups (25 per group). Each group was taught how to perform a basketball free throw using either a visual, aural or verbal learning style. The success of the learning style was determined by the number of points scored from ten attempts. Which of the following would be considered the independent variable?

Learning style of group

Before deciding which correlation test to run, which two assumptions need to be checked? (You may select more than one option.)

Linearity Normality

Which measure of central tendency is presented in a box-whisker plot

Median

15,467 people rated how much they liked my textbook on a scale of 1 (it is rubbish) to 10 (I love it). The distribution of scores had a skew of 1.23 (SE = 0.65). Which of the following would be the best way to decide whether the skew is problematic? (Hint: Think about what you know about the central limit theorem.)

None of the options, because of the large sample size.

Sports scientists were interested in the effects of anxiety and experience on high board diving performance. All three variables are correlated with each other, but what correlation test could be run if you wanted to find out the degree of 'exclusive' variance anxiety had on diving performance without the interaction of the experience variable?

Partial correlation

Assuming the appropriate criteria have been met, which correlation test would you run?

Pearson's coefficient

When discussing the concept of covariance, the distance from a specific observation (i.e. data point) to that of the mean of a given variable is known as:

Residual

Which of the following symbols does not represent a population parameter?

SD

A scatterplot shows:

Scores on one variable plotted against scores on a second variable.

The relationship between two variables partialling out the effect that a third variable has on one of those variables can be expressed using a:

Semi-partial correlation

Suppose you were interested in the relationship between body mass and basal metabolic rate and calculated an r value of -.79. How would you account for the variability between the two variables?

Square the r-value

Typically, research studies in sports science tend to recruit fairly small sample groups (less than 20), but what magnitude of effect can random data have on a data set?

Strong effect

The correlation between two variables A and B is .12 with a significance of p < .01. What can we conclude?

That there is a small relationship between A and B.

Which of the following statements about the F-ratio is true?

The F-ratio is the ratio of variance explained by the model to the error in the model.

What does the term 'residual sum of errors' (SSR) represent?

The extent to which the line of best fit reflects the data

What does m in a straight-line equation represent?

The gradient of the straight line

What does c in a straight line equation represent?

The intercept on the y-axis

When interpreting a correlation coefficient, it is important to look at:

The magnitude of the correlation coefficient. The significance of the correlation coefficient. The +/- sign of the correlation coefficient.

Which correlation coefficient would you use to look at the correlation between gender and time spent on the phone talking to your mother?

The point-biserial correlation coefficient, rpb

R2 is:

The proportion of variance in the outcome accounted for by the predictor variable or variables.

When we talk about the assumption of normality, what do we mean?

The sampling distribution of the parameter estimate must be normally distributed.

What purpose does the adjusted R2 value serve?

The variance in the outcome variable if the model was drawn from the population of the sample

The assumption of homogeneity of variance is met when

The variances in different groups are approximately equal.

A Pearson's correlation coefficient of -.5 would be represented by a scatterplot in which:

There is a moderately good fit between the regression line and the individual data points on the scatterplot.

If a correlation coefficient has an associated probability value of .02 then:

There is only a 2% chance that we would get a correlation coefficient this big (or bigger) if the null hypothesis were true

A Pearson's correlation of -.71 was found between number of hours spent at work and energy levels in a sample of 300 participants. Which of the following conclusions can be drawn from this finding?

There was a strong negative relationship between the number of hours spent at work and energy levels

If two variables are significantly correlated, r = .67, then

They share variance

What does the assumption of independence mean?

This assumption means that the errors in your model are not related to each other.

Why is it necessary to present numerical data graphically?

To enable you to 'make sense' of the data. To gain a greater insight into the data. To explore the data.

You determine an effect size from a study to be .04. How would this effect be categorized?

Very weak effect

Prior to running a regression analysis, what is the first procedure that should be completed?

Visually inspect the data using a scatterplot.

What is multicollinearity?

When predictor variables correlate very highly with each other

When it is not necessary to use Levene's test?

When you have equal group sizes.

Levene's test can be used to measure:

Whether group variances differ

The Kolmogorov-Smirnov test can be used to test:

Whether scores are normally distributed.

Percentage body fat cannot be measured directly, so it has to be predicted from a series of skinfold measures. Suppose seven sites were measured (triceps, chest, midauxillary, subscapular, suprailiac, abdominal and thigh). Suppose the abdominal and subscapular skinfold sites had a high degree of collinearity. What are the implications of this when attempting to predict percentage body fat?

all the above

Why is the sample size so important to statistical analysis, in this case during regression analysis?

all the above

Which of the following are assumptions of multiple linear regression?

alll the above

The test statistics we use to assess a linear model are usually _______ based on the normal distribution

parametric tests

We predict an outcome variable from some kind of model. That model is described by one or more _______ variables and ________ that tell us something about the relationship between the predictor and outcome variable.

predictor, parameters

What symbol is used to denote a correlation coefficient?

r

Imagine we took five people who each had one sibling and asked them how close they live to their sibling (km) (M = 12.40, SD = 16.32) and then asked them how many hours, on average, they spend with their sibling per month (M = 34.00, SD = 39.944). The covariance between the variables was −335.00. (a) Calculate the Pearson correlation coefficient r for the relationship between average time spent with sibling (hours) and distance from sibling (km). (Round your answer to two decimal places.)

r=-.51

Imagine we took five people who each had one sibling and asked them to rate on a 10-point scale how close they felt to their sibling (M = 6.00, SD = 3.06) and then asked them how many hours, on average, they spend with their sibling per month (M = 32.00, SD = 35.15). The covariance between the variables was 27.5. Calculate the Pearson correlation coefficient r for the relationship between average time spent with sibling and perceived closeness. (Round your answer to two decimal places.)

r=.26

The difference between each observation (i.e. hours of training and competition score) and the model fitted to the data (i.e. all observations) is known as:

residual

A _____ is a numerical characteristic of a sample and a _____ is a numerical characteristic of a population.

statistic, parameter