PSY-111 Statistics

When a constant value (such as 5) is added to each score in a frequency distribution, the mean will not change and will not be impacted.

FALSE- the mean will increase by 5.

For a _________ scale variable, a score or value of zero indicates that none of the variable is being measured.

Ratio

A sample mean is identified by using the greek letter "mu", (μ).

FALSE- the population mean is (μ) not the sample mean.

Temperature

Interval

A research design that uses the same group of individuals in all of the different conditions is called a repeated measures design.

TRUE

A sample statistic is described as being ___________ if the average value of the statistic either underestimates or overestimates the corresponding population parameter

BIASED

The value R^2 is called the __________________________ because it measures the proportion of variability in one variable that can be determined from the relationship with the other variable.

Coefficient of determination

_____________ is a statistical technique that is used to measure and describe the relationship between two variables.

Correlation

The pearson correlation for a population is identified by the letter r and the corresponding pearson correlation for a sample is identified by the greek letter rho (P)

FALSE r is for sample P is for population

For the independent measures T-statistic, if two samples have sizes n1=10 and n2=12 the appropriate degrees of freedom is computed as df=n1+n2 -1. DF=21

FALSE its 22**

The following is the correct statement of the null hypothesis for a repeated measures hypothesis test: H0: μD>0.

FALSE the null hypothesis for a repeated measures would be H0:μD≠0.

A parameter is a value- usually a numerical value- that describes a sample. A parameter is usually derived from measurements of the individuals in a sample.

FALSE- A parameter describes a population. A statistic describes a sample

A bar graph for nominal level data is essentially the same as a histogram because no spaces are left between adjacent vertical bars.

FALSE- Bar graphs have visible spaces

The boundaries for the critical regions are determined by the alpha level. If sample data fall in the critical region, the null hypothesis is not rejected.

FALSE- H0 is rejected because it is an unlikely outcome.

An independent measure study comparing two treatment conditions uses one group of participants and one score for each participant.

FALSE- Independent measures study comparing two treatments would use 2 groups with 1 score for each participant.

The T-statistic is used to test hypotheses about an known population mean, when the value of σ is known.

FALSE- It is used to test unknown population mean when σ is unknown.

When a distribution of scores is skewed and has one or more very extreme values, the mean is the preferred measured central tendency.

FALSE- The median is the preferred measure of central tendency.

A type 1 error occurs when a researcher fails to reject a null hypothesis that is in fact false.

FALSE- Type 1 error occurs when the researcher rejects a null hypothesis that is true

A sample statistic or deviation score is the difference between a score and the mean.

FALSE- Unbiased

As the degrees of freedom decrease, the shape of the t-distribution becomes more similar to a normal distribution.

FALSE- as the DF INCREASES, it becomes more like a normal curve.

As the chosen level of confidence increased, the width of the confidence interval constructed using the t-test will decrease.

FALSE- as you increase the confidence, the width also increases.

correlation coefficient can have the values between -1.00 and 1.00. A strong coefficient of +.90 can be interpreted as describing a casual relationship between x and y where increases in one causes an increase in the other.

FALSE- closest to 0.00 is the best

For the T-distribution for a single sample, the degree of freedom are calculated as df=n+1.

FALSE- df=n-1

The hartley's F-Max test involves calculating the ratio of the smallest sample variance to the largest sample variance.

FALSE- it is the largest on top and the smallest on the bottom.

A study comparing cholesterol levels before and after diet featuring oatmeal is an example of an independent measures design.

FALSE- measuring before and after is a repeated measures design.

Another measure of effect size we reviewed is r^2 which estimates the percentage of variability that is not accounted for by the treatment effect.

FALSE- r^2 is used to determine how much of the variability in scores is explained by the treatment effect.

In general, a linear relationship between two variables x and y can be expressed by the equation Y=bx+a. The value of a is the x-intercept and it determines the value of X when y=0.

FALSE- the value of A is the Y intercept.

A researcher conducts a repeated measures study and has 40 total data values. We know that there was probably 40 subjects in the study.

FALSE- there was probably 20 subjects.

A frequency distribution histogram cannot be constructed for grouped data values.

FALSE- we can build a histogram where we show the labeling along the y axis.

When the T-test for independent measures is used to analyze data, as the adjusted or computed combined sample size increases from a small n to a much larger n, the likelihood of rejecting the null hypothesis decreases.

FALSE- when you increase the sample size, the likelihood of rejecting null hypotheses increases.

The law of large numbers states that the larger the sample size (n), the less probable it is that the sample mean will be close to the population mean.

FALSE- with the larger the sample size, the MORE probable it is that the sample mean will be close to the population mean.

A correlation of r=.80 means that 80% of the variability in the Y scores can be predicted from the relationship with X.

FALSE- you need to square r to find the percentage. r=64%

A researcher expects a treatment to produce an increase in the population mean. Assuming a normal distribution, the critical z-score for a one tailed test with α= 0.1 is +2.58.

FALSE- z score of 2.33 has a tail of 1% not 2.58.

The T-distribution approximates the shape of a bimodal distribution

False- It takes on the shape of a normal distribution.

Upper and Lower real limit of 155

Lower- 154.5 Upper- 155.5

The _________ is the only measure that can be used to measure and describe central tendency for data measured on a nominal scale.

MODE

In descriptive statistics, the measures developed for measuring central tendency include the __________,__________,__________.

Mean, median, mode.

In a graph of a__________ skewed distribution, the scores pile up on the right side of the chart and the tail tapers off on the left side.

NEGATIVE

clothing size (S,M,L)

Ordinal

A ___________ is the set of all the individuals of interest in a particular study.

Population

The measure of variability which is the distance covered by the scores in a distribution from the lowest score to the highest score is the __________.

Range

Three different measures of variability include the ___________,___________, and ___________.

Range, variance, Standard Deviation.

For a graph of ___________ distribution it is possible to draw a vertical line through the middle of so that one side of the distribution is a mirror image of the other side of the distribution.

SYMMETRICAL

A deviation or deviation score is the difference between a score and the mean.

TRUE

A frequency distribution is an organized tabulation showing the number of individuals located in each category on the scale of measurement.

TRUE

A sample is a set of individuals selected from a population, usually intended to represent the population in a research study.

TRUE

Adding a value of 5 to each score in a frequency distribution does not change the standard deviation for that distribution.

TRUE

Difference scores are computed and then used as one source of the input data for calculating a repeated measures t-test.

TRUE

For the T-distribution, one basic assumption underlying the independent measures t formula is that the values in the sample must consist of independent observations.

TRUE

In a grouped frequency distribution we show groups of scores rather than individual values.

TRUE

In general, a linear relationship between two variables X and Y can be expressed by the equation Y=bx+a. The value of b is called the slope and it describes the amount that y changes each time x increases by one point.

TRUE

In the context of an experiment, null hypothesis (Ho) predicts that the independent variable (treatment) has no effect on the dependent variable (scores) for the population.

TRUE

On average, the sample variance s^2 provides an accurate an unbiased estimate of σ^2 the population variance.

TRUE

Sample variance is represented by the symbol S^2 and equals the mean squared distance from the mean. Sample variance is obtained by dividing the sums of squares (SS) by n-1.

TRUE

Sampling error is the naturally occuring discrepancy, or error, that can exist between a sample statistic and the corresponding population parameter.

TRUE

The T-distribution is symmetrical with a mean value of 0.

TRUE

The estimated standard error (SM) is used to estimate the real standard error (σm) when the value of σ is unknown.

TRUE

The estimated standard error of M1-M2 is calculated using the pooled variance estimate.

TRUE

The mean and or median do not necessarily have to appear as actual data values in the data set being analized.

TRUE

The mean of the distribution of sample means is equal to the mean of the population of scores, μ, and is called the expected value of M.

TRUE

The pearson correlation measures the degree and direction of the linear relationship between two variables

TRUE

The pearson correlation measures the degree and direction of the linear relationship between two variables.

TRUE

The power of a statistical test is the probability that the test will correctly reject a false null hypothesis. That is, power is the probability that the test will identify a treatment effect if one really exists.

TRUE

The statistical technique for finding the best fitting straight line for a set of date is called regression and the resulting straight line is called the regression line.

TRUE

Two general categories of statistical procedures include Descriptive statistics and Inferential statistics.

TRUE

When the T-statistic is used for a hypothesis test and the result is statistically significant, a recommended next step is to used the estimated cohen's d test to compute a measure of the effect size.

TRUE

______________ provides a quantitative measure of the differences between scores in a distribution and describes the degree to which scores are spread out of clustered together.

Variability*

political affiliation

nominal