T-tests

Question 1

Estimated Standard Error

Answer 1

the standard error using sample variance versus population variance, since population variance is generally unknown

Question 2

Estimated Standard Error Formula

Answer 2

sm=sqrt s^2/n=SD/sqrt n

Question 3

T-Distribution

Answer 3

A sampling distribution derived from the sample variance, not the population variance

Question 4

DF for t-distribution

Answer 4

n-1, amount in the distro tail decreases with fewer degrees of freedom

Question 5

T-table

Answer 5

A table of “critical values” for the T-distribution

Question 6

Z vs T formula

Answer 6

z=M-μ/σm

t=M-μ/SD/√n

Question 7

Comparison

Answer 7

Tobt is < or > or = Tcritical

Question 8

One Sample t-Test (Independent) assumptions

Answer 8

Assumptions made:

1. data are normally distributed
2. data were obtained using random sample
3. probabilities of each outcome in study are independent (there is no influence, sampling with replacement etc)
4. Degrees of freedom will be used

Question 9

Confidence Interval (CI)

Answer 9

A scope or range of values that could possibly contain the population parameter we’re inferring

Question 10

Point Estimate

Answer 10

A sample statistic (usually a single value) given as a probable population parameter

Question 11

Level of Confidence

Answer 11

The probability that an estimate of interval will contain a particular population parameter

Question 12

Estimation

Answer 12

A statistical method where a sample statistic is used to estimate an population parameter, which often isn’t known.

Question 13

Degrees of Freedom

Answer 13

n-1 for the t-distro: the number of sample items that is allowed to vary.
Increases with sample size

Question 14

Estimated Cohen’s D

Answer 14

The estimate of effect size used with t-tests: sample standard deviation (SD) is used instead of population standard deviation (σ)

Question 15

estimated standard error

Answer 15

Since, on average, the sample variance is an “unbiased” estimator of population variance, we can substitute it into the standard error formula

Question 16

Estimated Standard Error formula

Answer 16

SD/√n

Question 17

t-statistic (Tobs/Tobt)

Answer 17

Inferential stat that helps determine, in t-distro, the number of standard devs that a sample mean deviates from the mean value OR mean difference in the null.

Question 18

t-distribution

Answer 18

A distribution very similar to the normal, except that the further out you go, the more spread the scores are because of the greater variability of sample variance.

Question 19

Proportion of Variance

Answer 19

An estimate of how much the difference observed in an experiment caused can be attributed to their treatment

Question 20

Proportion of variance formula

Answer 20

Prop of var= variability explained/total variability

Question 21

Eta-Squared (η^2)

Answer 21

A measure of proportion of variance using t-statistic and degrees of freedom

Question 22

η^2 formula

Answer 22

η^2=t^2/t^2-df

Question 23

omega squared formula (ω^2)

Answer 23

ω^2=t^2-1/t^2+df

Question 24

Omega-Squared

Answer 24

A more conservative estimating statistic of proportion of variance, since Eta-Squared tends to run high

Question 25

treatment

Answer 25

A procedure done to a randomly sampled proportion of a sample to produce a specific variance and test hypotheses